


Communication Breakdown

by fionasank



Category: Doctor Who, Sherlock (TV), Supernatural
Genre: Angst, Gen, Horror, Multi, Suspense, idk - Freeform
Language: English
Status: Completed
Published: 2013-10-12
Updated: 2014-01-31
Packaged: 2017-12-29 06:02:18
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 6
Words: 22,978
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1001852
Author URL: https://archiveofourown.org/users/fionasank/pseuds/fionasank
Summary: <blockquote class="userstuff">
              <p>A demon lures the SuperWhoLock gang into an abandoned building, where it proceeds to possess one of them at a time, and no one has any idea who.</p>
            </blockquote>





	1. Prologue

_Let's set the scene, shall we?_

_A busy London street. Usual kind of day; occasional cloud in the sky, frequent winds, a little edge to the curt breeze. People walk around, holding shopping bags and phones and each other. I survey my targets: a jogger passes me by. Oh, yeah. Perfect cover. I shove myself into her mouth. Slim, strong build. She flexes (I flex) her arms. Perfect._

_I've already observed that they're heading my way, so she ducks (I duck) into a storefront and drink from her water bottle. A child walks by. I blink. He cries. Excellent._

_A few minutes later, she hears (I hear) him talking like a madman. His voice floats to her ears above the crowd. Ridiculous._

_"...so I_ told _Cleopatra, I've never seen you before in my life! And she said, 'yes, you were here last week!' Then she started to describe a man who called himself the Doctor, with a bow tie and a tweed jacket and I stopped her 'cause she must have been describing my next regeneration. Imagine that! A bowtie!"_

_They come into view now, walking so quickly that jogging behind them won't appear suspicious. The blonde girl shoves chips into her mouth, licking at her fingers while glancing frequently up at the man, who gestures so wildly with his hands it's a miracle he doesn't hit a passerby._

_She sets (I set) off, keeping a few metres behind them. I assume this man is the Doctor. The girl must be Rose Tyler. It was surprisingly easy to find them; they're very loud._

_I listen closely. Yes, there it is. The faint buzz of his psychic paper. Humans must be rubbing off on him – doesn't he realise that if a signal can be sent to the paper, it can be tracked? Well, I can track it. But he's never met someone like me before._

_Really, Doctor. You need to pay more attention when you come to Earth._

_The Doctor and Rose Tyler turn a corner into a small, uninhabited alleyway. She waits (I wait) by its entrance, looking in._

_Oh, Lucifer. There it is._

_I've been hearing it for so long now, from miles away, even through time. The low music of the TARDIS. Oh, how I'd love to sink my teeth into that sexy thing. But there are more important matters at hand._

_He fishes out his keys, still yammering on about something or other. Rose still stares at him, hardly blinking, offering a witty quip every now and then. It's time. I do as I've always been planning._

_"Wait!" she calls (I call) out as she runs (I run) towards the blue box and the human and the Time Lord._

_They both turn around. "Hello," says the Doctor, grinning. She hunches (I hunch) over as if she's (I've) been running for a while. "Psychic paper," she wheezes (I wheeze)._

_The Doctor's face immediately becomes serious, handing her (me) the small leather wallet. "What, you're just gonna give it to her?" asks Rose in disbelief._

_"I think she needs help," murmurs the Doctor. She nods (I nod) as she places (I place) her thumb against the surface of the paper. I transfer the address and timestamp onto the page, watching as it appears in black capital letters. She shoves (I shove) the wallet back into the Doctor's hands, saying, "Please help," as she looks (I look) into his eyes, pleading. He frowns, beginning to say something, before she runs (I run) off. Perfect. Well done._

_I leave the jogger. She collapses, hits her head hard on the pavement. Blood pools. I'd laugh, if I were currently capable. That's one for the scrapbook._

_One out of three._

* * *

_Across the pond, now. Same day. Sioux Falls, South Dakota, United States, America, Earth, the Solar System, etc. An old house. It smells weird._

_I've been following the boys for weeks now, I know their routine. They cry a lot. It's rather pathetic. If I get a hold of Sam, I'll cut his hair, among other things. I'd be smiling if I had a mouth. I'm excited._

_I'm a woman again. Annoying. She runs (I run) quickly to the house, seeing as she's (I'm) about a mile out. Smack the old drunk on the head in his sleep, burn off his tattoo, climb on in. The woman wakes up. He slits (I slit) her throat quickly._

_Bobby Singer picks (I pick) up the phone and hits (hit) speed dial 1 – direct line to all that's left of the Winchester family. I can laugh now. He does (I do)._

_"Hey, Bobby, what's up?" asks Sam, voice loud and irritating. I do my best Bobby Singer impression._

_"You boys working a case?" he says (I say). I throw enough quiet desperation and muted intoxication in to make it believable._

_"Nah, just finished one up." I knew that. Bobby does not. Hey, now he does. Everybody wins. "Why, you got something for us?"_

_"Well I got a call from Rufus this morning, tellin' me to meet him at an address at 9am tomorrow. I won't be able to make it in time, you two mind checkin' it out?"_

_"Sure, gimme the address." That's it. No hesitation. Immediate compliance. I love my job. He reads (I read) the address to Sam, who thanks me and hangs up._

_And that's it. I thank Bobby, who yells the exorcism at me. Not gonna work inside your head, old man. I lock him in his saferoom for good measure, though it's unlikely he'll wake up from that head wound anytime soon. Or the knife wound. Heh, couldn't help myself. He has a lot of flesh._

_I (would) smile as I leave, picturing the Winchesters opening a door in one country and shitting themselves in the next._

_Two out of three._

* * *

_Again, London. Same day, forty miles East. I'm glad I saved this one for last. I'm a sucker for detective stories._

_They don't go out as much, these two. I observe their flat. I've been aching to go inside for weeks. I bet the air tastes sublime._

_I nab a guy out in the street, a businessman who looks like he's late for something. He laughs (I laugh). "Sorry, dear, not your morning," he says (I say) to himself (him). I make my way up the stairs and ring the bell for 221B._

_A few minutes later, John Watson opens the door. I swear he only has three interchangeable jumpers – but I guess I'll find out soon. My fingertips tingle with excitement._

_"Yes, hello?" John says, looking exhausted._

_"I have a case for Mr Holmes." I hate this guy's voice. I tell him so. He prays. I roll my eyes internally at him._

_John's eyebrows shoot up. So many emotions. Aw, poor little fool. "Really. You sure?"_

_He frowns (I frown). "Yes. Everything alright?"_

_"Yeah, it's just, Sherlock can usually tell with these things." He steps back to allow him (me) in. "Come on in, Mr..."_

_A social cue. I read the man. "Collins. Jay Collins."_

_"Mr Collins," John finishes, closing the door behind us. "This way." He leads him (me) up the too-creaky steps and asks me to hold on. He listens (I listen) to their conversation from behind the door._

_"Sherlock."_

_Pause._

_"SHERLOCK."_

_"Hm? What?"_

_"Client."_

_"Ha."_

_"No, there's a client just outside the door."_

_"Your wit is improving, John. We both know that the ring of the doorbell wasn't right."_

_"For God's sake, put your shirt on."_

_"Oh. You're serious." Fabric rustles. "Interesting. Bring the man in."_

_"How – oh, I give up."_

_The door opens – John smiles sheepishly. I've seen puppies that are more guarded with their emotions. Worry teems off him in visible lines._

_He sits (I sit) on a squidgy armchair. John sits opposite on a hard black one. Really. You'd think the metaphors would be subtler. Oh, I do wonder whose chair is whose! Sherlock paces. He grips (I grip) the arms of the chair in anticipation._

_"You're late for your meeting," Sherlock says. He's looked at him (me) exactly once._

_"Sorry?"_

_"It's very important. You might get promoted, and then your wife can afford to furnish the baby's room."_

_He gapes (I gape). "It's... an urgent matter."_

_"Obviously." He frowns. "Hm. Go on."_

_"I received a note in the post last night." He pulls (I pull) it out of his pocket (thin air)._

_"Post doesn't come at night," John tries._

_"It just came through the door." He hands (I hand) John the note. It's pristine, typed in Times New Roman. An address, a timestamp, and an instruction: 'Tell Mr Holmes and Dr Watson to come alone.'_

_John reads it aloud them holds it behind him; Sherlock snatches it up on his way past. That man. Artwork. He scans it, turns it over. Smiles. Smiles? Wonderful._

_"A trap?" muses John, leaning back, obviously uncomfortable in the harsh chair._

_"Almost definitely," Sherlock replies, voice throwaway, passive._

_"Will you go?" he asks (I ask). I throw in some fear for my own life._

_"Of course." Sherlock turns to me, grins. "Love a good trap, haven't had one for years now." John rolls his eyes. He's not so bad._

_Sherlock dashes off to the kitchen, begins running tests on the note. John asks him (me) routine questions: where were you last night? what time did it arrive? do you have any enemies? I sigh and access the man's memories. I hate legwork._

_"Don't bother John, he's not of use," calls Sherlock amidst a loud clatter. "Except –"_

_Suddenly he's in front of me. "How did you hear about us?"_

_"What?" he asks (I ask)._

_"The man writing the note, he was sure you'd know of us. Didn't even include our address."_

_He waits impatiently, fingers tapping Bach on his hips._

_"The telly," he says (I say), as it's true of the man. "That Reichenbach case last week. Brilliant case. Good work, by the way. Astounding."_

_At this he appears rather taken aback, an expression which fits him ill. "I – uh. Thank you. You can go. Leave your number with John." He runs off once more, leaving him (me) to give his (Collins's) number to the pet. They (we) shake hands. He leaves (I leave). I leave._

_Exhilarating. Orgasmic. I cannot wait to play with that mind further._

_Three out of three._

_The game's afoot._


	2. When The Levee Breaks

"It's probably a trap."

"What was that?" The Doctor pokes his head up through the TARDIS's maintenance hatch, the rising steam covering his face with a thin sheen.

"It's probably a trap," Rose repeats, leaning against the console, picking at her fingernails with a fragile casualness. "Aren't there any, I dunno, _checks_ you can do?"

The Doctor gives her a mockingly stern, scolding look. "Now what kind of way of life is that? Checking everything before you do it, no fun at all! I've been leaping into things my whole life, and look at me, I'm as healthy as a two-hundred year old!"

Rose purses her lips. She's learned by now to not let the Doctor's perpetual flippancy get to her. If he's going to listen to her, she needs to stay calm and make her point rationally.

"You're an idiot." That works too, she's found.

He just grins. It looks good on him. "Rose, ninety-nine percent of the situations I wander into on a daily basis are traps, and I am one-hundred percent okay with that." He ducks back down into the controls and Rose thinks about how he said "I", and not "we", and whether he meant anything by it.

Since becoming his companion, Rose has discovered a few new self esteem issues cropping up every now and then. It's a bit intimidating to travel with someone who's had more girlfriends than you've had haircuts, but she knows he's not like that. It's not that he's a _player_ , for God's sake, he's too innocent and wide eyed for a thing like that. It's just... he's just old. And she's just young. That's all it is.

She hums quietly to herself as the Doctor prepares them for flight. She watches as he fiddles and fixes and looks at her every ten or so seconds and smiles to make sure she's still watching him be clever.

Pushing herself off the console, she says, "If we get kidnapped, chips are on you," and walks away laughing as the Doctor protests loudly. She's worried sick about what's waiting for them, a fact that she'd never tell him, but whatever happens, she knows she'll be by his side forever.

* * *

The cold air of a London morning does nothing to warm the manner of Sherlock Holmes. On the contrary, his cool manner seems to be made even cooler by the fact that he doesn't have his scarf.

"I told you press attention was a bad idea. Probably one of my fans breaking in to get a memento. Better yet, something to sell on the internet. _Scarf of the famous detective! Wear it and pretend you're not a moron!"_ He continues like this for several minutes, grumbling and threatening and trying to work out who could have taken it despite the fact there was no evidence whatsoever. "So most likely a professional thief. I'll look on eBay for it when we get back."

John hums his agreement, still looking through his binoculars at the door. Sherlock glances at him, sighs, and returns his own to his eyes.

They've been waiting here since 8am, trying to work out what on Earth the note had been about, and why they've been summoned. Their hiding place behind the bins is neither glamorous nor comfortable, but those qualities don't usually apply to life with Sherlock anyway. So far there's been no action. But it's nearing 9am, and Sherlock's getting restless.

"I'm _bored_ ," he moans, dropping his binoculars in his lap again and throwing his arm over his eyes. "There aren't any _clues_ , I need to get in there!"

"Five minutes, Sherlock, five minutes and we'll go in." John hasn't once taken his eyes off the entrance to the building, keeping a rigid stance as every soldier should be able to do.

"If this is Mycroft, I'm not pulling any punches this time. Literally. I still remember the first time he tried to throw me a surprise birthday party, I couldn't sit down for weeks, the burns were so bad." He turns up his coat collar, pulling it tight around his exposed neck.

"What the hell – nevermind, I don't want to know what Mycroft did to your arse," John sighs from his post.

Sherlock pouts slightly, disappointed. He loves telling that story. Wait, that's not right. He thinks John would love hearing it, is the thing.

Growing bored, Sherlock pulls out his phone and hacks into the local doctor's, optician's etc until he finds one of Anderson's appointments, which he promptly moves to later today just to mess him around a little. He also changes the gender to female and the age to eighty-nine. Not his best work, but he's working with limited resources here.

"Sherlock," John says suddenly, with urgency. Sherlock looks up, pulling his binoculars to his eyes.

A tall, skinny man with a long coat and a pretty blonde girl are smiling and laughing and approaching the building. The man pulls something out of his pocket that looks suspiciously like a screwdriver and uses it to scan around them, before frowning and putting the thing away. He and the girl slip inside the building.

"They just wandered in!" John exclaims, finally leaning back and turning to Sherlock. "Why would they just –"

He's interrupted by Sherlock standing and following the unknown couple into the building.

"Oh, for God's sake – Sherlock!"

* * *

Rose takes one look at the dank walls of the hallway and stained windows and dirt and grime and says, "This is horrible."

"Oh, it's not _that_ bad. I've had worse, let me tell you. You don't wanna go into the bathroom after Henry VIII." The Doctor wanders over to the window, sliding his finger along the pane and then licking it. "We're on Earth, that's a plus."

"Of _course_ we're on Earth."

"Still, got to be sure. Could have been a spatio-temporal hyperlink."

"What's that?"

"Better term for 'magic door'."

She narrows her eyes. "You've said that before."

"Yeah, but it was funny, and I wasn't sure you'd heard me." He grins and it fills his face. "Good to know you're on the ball."

They both spin around suddenly as the door opens and a tall man in a dark coat and some _great_ hair walks – no, _strides_ – in, and Rose immediately feels like she should tuck her shirt in.

The man stops walking and the three of them look at each other for a moment.

"Hello!" says the Doctor eventually.

"Who are _you_?" Rose asks, and it comes out more impressed than she'd meant it to.

"Sherlock Holmes. And you?" His voice is low and rumbly. Rose holds in a wolf-whistle.

"I'm Rose, this is the Doctor." She sticks out her hand for him to shake. He doesn't acknowledge it, instead saying, "This is my friend, John Watson."

Rose looks around; there's no one else here. "Who do you –"

The mystery solves itself as a short blonde man comes crashing through the door, breathing slightly heavily and looking around himself wildly. He spots Sherlock and strides up to him, muttering "stupid arrogant twat what if _I_ left then huh where would you be who would get the bloody milk _then_ ".

Sherlock stops him by turning away and saying, "John, this is Rose Tyler and the Doctor."

John freezes, realising their presence. He turns to the two, visibly swallowing his anger, before taking Rose's hand, which she hadn't realise was still extended. "Hi. John Watson." He holds his hand to the Doctor, too, who shakes it gleefully.

"You're a doctor?" he asks the Doctor, smiling a little.

"Technically, yes."

"Me too. Looks like we're prepared for any accidents." He sees Rose's frown and says, "I'm assuming you got a note to be here too?"

"Yeah," Rose replies before the Doctor can explain just how weird their note really was. They're trying to be inconspicuous, for God's sake. No need to go on about _aliens._ And hell, if it was a trap – which she still swore it was – they'd all find out soon enough.

"What do you do?" Sherlock says suddenly, turning to Rose.

She blinks, bewildered. "Oh. I'm a traveller, I suppose. Just kind of drifting at the moment."

Sherlock narrows his eyes. "Where?"

"Europe," she says in panic.

"You're lying."

Rose feels the Doctor move ever so slightly closer to her; unconscious protection. "Where d'you get that from?" she replies, keeping her voice calm.

"There's dirt on your jeans unlike any soil type in Europe, or even on Earth."

"How can you tell?"

"It's pink."

Rose opens her mouth to provide a feeble reply when there's another loud crash and three men fall out of the front door. Two of them fall on each other and one steps gracefully over them, looking down at his companions in concern.

"You should probably stand up," he says to them in an American accent, his voice impossibly low and powerful. He looks strangely uncomfortable, as if he's in someone else's body; his trenchcoat and suit hang on him as if he's not aware he's wearing them.

She hears a grumble of "goddamnit" and another voice saying "get _off_ me" before the two men stand up, brushing themselves off, guns in hand. One of them is taller than the other, and they both wear jeans and plaid.

The three newcomers look around, slightly overwhelmed. "This isn't an ambush, is it?" says the tall one.

"No, they're not demons," says the one in the trenchcoat.

"What?" John says in disbelief. "What's that about demons?"

"He's kidding, of course," says the blonde one, clapping his hand on trenchcoat's shoulder. "He just means you look like nice people." He changes the subject quickly by looking around and saying, "Why is it light outside?"

The tall one looks up and says, "Oh. I, uh – wow, that's weird."

"We seem to have changed time zone," says trenchcoat. "We are now in London, England, and it's 9:07am."

"England?" the blonde one says in disbelief. He turns to Sherlock. "You English?"

"Obviously," Sherlock replies. "How did you get here?"

"No idea. We were in California and then – poof. We're here."

"Wait, who _are_ you?" the tall one says to the four people he doesn't know.

"Oh, right. Where are my manners," the Doctor says brightly, stepping forwards. "I'm the Doctor, this is Rose Tyler, my trusty sidekick –"

"I prefer the term companion," she cuts in.

The Doctor pouts. "But sidekick makes me sound like a superhero!"

John clears his throat. "I'm John Watson, this is Sherlock Holmes. Now, you?" Rose spots that his hands are behind his back. She strongly suspects that he's drawn his gun.

The tall one and the blonde one exchange a glance, with the blonde one nodding slightly. The other takes a deep breath and turns back to the rest. "Well, I'm Sam, and this is my brother, Dean. And this –"

"My name is Castiel. I'm an angel of –"

Dean coughs loudly, covering up the rest of Castiel's sentence. "Ha, he's kidding again. Real religious, this one. He's Cas. Call him Cas." Cas looks at Dean in confusion, but doesn't comment.

"Did you get a note too?" John asks Dean, who appears to be in charge.

"No, why? Did you?"

John nods simply, and Dean frowns. "Well, we got a call that something strange was going on up in California. We went to check it out. We're FBI." He draws his badge.

"No you're not," Sherlock says.

Dean glares at him. "Excuse me?"

"That's a fake badge."

"Where do you get off saying _that?_ "

"No, no," John says suddenly, waving his hands in front of him. "Don't get him started. There are more important things to be talking about at this moment."

"Yes, you're right John," Sherlock says, to which John opens his mouth in surprise. Sherlock points to Cas, saying, "Namely, why has that man not eaten in years?"

* * *

_The lights go off. I enter._

* * *

"Everybody stay calm!" Rose hears Dean yell as the room goes black. A hand grabs hers, fingers threading in, warm and comforting. "Cas, can you see?"

"No." Cas's voice is strained and worried. "Dean, I – I can't. I think something's draining my power."

" _What_?" Dean shouts. "Oh, you gotta be _kidding_ me!"

The lights snap back on suddenly and Rose shuts her eyes, crying out, momentarily blinded. She blinks slowly, squinting around. Everyone is still there, everyone seems to be alright.

Except John, who has his head in his hands.

"John?" Sam says, making Sherlock turn and realise the state of his friend. "You okay?"

Dean whispers something in Cas's ear, to which Cas's brow furrows and he says, "I can't tell. I can't see."

John drops his hands and opens his eyes. They're black.

"Woah!" Rose cries, taking a few steps back, as do the Doctor and Sherlock. The Americans, however, seem to have expected this.

"Sammy, salt water!" Dean says quickly as his brother searches his pockets. "C'mon!"

"Dean, it's not here!"

"Don't tell me you forgot it!"

" _No_ , I definitely had it, I always have it –"

"My bad," says John, causing the brothers to stop their argument and turn to him immediately. "Must have misplaced it for you." His voice is different: lower, calmer. Colder.

"What _is_ that?" Rose cries. She looks to the Doctor, who's peering at John with curiosity, but no fear. Sherlock, however, is full on staring, wide-eyed and tight-lipped, hands visibly clenched in the pockets of his coat.

"It's a demon," says Sam, anger and confusion clear in his voice. "Also, kind of a dick."

John smirks. "There's that Yank charm I've heard so much about."

"Hold on, a _demon?"_ Rose throws her hands in the air. "Like, an _actual demon?_ "

"Welcome to our world, gorgeous," Dean quips without taking his eyes off John.

"What did you do to me?" says Cas, low and threatening, and Sam and Dean turn to him; Sam in surprise, Dean in concern.

"Oh, don't get all mad. It's a simple matter of sigils. One to trap you in, one to drain your powers." John hasn't moved from where he's standing, hands clasped in front of him, his stance much more relaxed than usual.

"Man," Dean says scathingly, "I thought _angels_ were douchebags -"

John waves his hand lazily and Dean stops talking immediately, eyes widening and scrabbling at his mouth. "That's enough out of you," John says, and Dean realises what's happened and glares, arms folded across his chest.

"Allow me to explain the rules."

Rose retakes the Doctor's hand.

"If any of you try the exorcism, I'll kill you immediately. The door is locked, and there's no chance of escape. Not that any of you cared to check, damn hero complexes. I will possess one of you at a time, and none of you will be able to tell who." He begins to pace, weaving in between people, not touching any of them. "I'll have complete access to your thoughts, feelings, memories, so I can mimic you very accurately, so much so that even your partner won't be able to recognise you." Suddenly he sighs, irritated.

* * *

_The lights go off. I change._

* * *

"Dude, not cool!" Sam yells as the lights come back on, throwing an arm over his eyes. Dean has his gun held in front of him. Sherlock hasn't spoken in a while, and even though she hasn't known him for that long, Rose knows that this isn't usual behaviour for him.

"Why d'you have to bring the _angel?_ " Cas says in an English accent, and Rose turns to him to see that his eyes are now black instead. She glances to John. He's getting up off the floor, and Sherlock is helping him, asking if he's alright, to which he nods.

Sam and Dean, however, are not. They take a few steps back from Cas, shock on their faces, Sam drawing his gun as well. "What the Hell?" Sam shouts, pointing his weapon at Cas's head.

"How did you possess _Cas?"_ Dean asks loudly, in complete disbelief.

Cas ignores them, looking at his hands. "God, he's gonna go tell on me, isn't he? Run to daddy or something, I'm gonna be hunted, damnit. And I was gonna do pairs, like turn you against each other, but now it doesn't make _sense_ that I said _'your partner won't be able to recognise you'_ because you brought the bloody angel!"

"Well," says Dean, clapping his hands together once in front of him. "Why don't you just let him go, and we can do _your_ thing?" He gives Cas the most overtly charming smile Rose has ever seen.

Cas just rolls his eyes, fading them to normal colour. "Nice try, muscles." He wrinkles his nose and Dean's smile drops immediately as he looks away. "I don't like this. He keeps trying to push me out. No offence, but he's a hell of a lot stronger than you," he says to John, who's also drawn his gun and has his jaw tensed dramatically. "Okay. Brb."

* * *

_The lights go off. I change._

* * *

"Is everyone alright?" says the Doctor, glancing from John to Cas to everyone else. No one's eyes are black.

"Where are you, you bastard?" Dean says, pulling out a torch and shining it into everyone's eyes. "Cristo!"

Nothing happens.

"What the _fuck_ ," Dean mutters under his breath, turning to Cas and placing a hand on his shoulder. "You okay?"

Cas nods, sweat clear on his face. "I don't know how that happened. In theory, it's impossible for me to be possessed."

"Dean, if the demon can get in _him,_ does that mean..." Sam trails off, raising his eyebrows.

"That it can get in us?" Dean frowns. "Maybe, yeah. We gotta be on the lookout."

He turns to the rest of them. "Right, so, one of us is possessed, and we have no idea who."

"You must be joking," breathes John, lowering his arm, but not putting his gun away. "How is this possible?"

"Oh, anything's possible, really," the Doctor pipes up, positively grinning. "Just because it's not logical, doesn't mean it's impossible."

"I have to agree." Rose turns as Sherlock speaks, his voice normal. "Once you eliminate the impossible, whatever remains, however improbable, must be the truth."

"Oh, what, and _demons_ aren't impossible?" Rose cries.

"Not technically."

"How do you figure?"

"There is no solid evidence against it, and there seems to be a lot of evidence _for_ it, as of the last few minutes." He wipes a hand down his face. "It's real."

"If we could get a word in edgeways," says Dean, holding up his hand, looking annoyed. "Yeah. Demons are real. So are vampires, so are werewolves, so is practically everything you've ever had nightmares about."

"How do _you_ know?" asks John, ever the sceptical.

"Because it's our job to know. You wanna survive, you listen to us."

"Hang on, who put _you_ in charge?" Rose says.

Dean smiles. "Well, from looking around the room, it's pretty clear that we're the strongest, we're the _tallest_ , and we know the most about demons. Now c'mon, we should scout the area." Rose notices for the first time that the hallway leads to multiple rooms and continues, both to her left and right, round corners.

"If you know so much about demons, why are we still here?" demands Sherlock in a subtle tone. "Why are we here in the first place? If you're as well informed as you say, we wouldn't be in this situation, and neither would you."

Dean stares at him. "Sorry, who are you?"

Sherlock smirks, saying, "Of course you don't know who I am. I highly doubt you bother watching the news. My name is Sherlock Holmes, I'm a consulting detective."

Rose interrupts Dean's muttering of _what the Hell is that_ by saying, " _There's_ a plan. If we're gonna be stuck here together, we should introduce ourselves." She turns her gaze to Dean, glaring a little at him. "You first, Rambo."

He raises his eyebrows at her, waiting for a few seconds before talking to see if she's serious. "Alright," he says eventually. "Hey. I'm Dean, I'm an Aquarius, I like long walks on the beach and frisky women -"

"Give me a break," Sherlock mutters.

"I'm a hunter," Dean continues, louder, "meaning I hunt the supernatural for a living with my brother Sam here, and our feathery friend Cas."

"Wait, so he's really an angel?" Rose asks, staring at Cas. He stares right back at her, quizzically.

"Yep, equipped with wings and Grace and all. But he's not working right now." He pats Cas on the shoulder encouragingly. "Still great though."

"Thank you," Cas replies, missing the point a little. "Hello, everyone." He nods stiffly.

"Sammy?"

"Oh, okay," Sam says, and clears his throat. "Right, well, I'm Sam. Basically what Dean said, really. We know what we're doing. You're in good hands."

Sherlock snorts, and John elbows him. "What?" Sherlock says, turning from John to Sam. "We're not _in_ your hands. We're in the hands of this villain."

"Well, uh. I mean." Sam scratches the back of his neck. "We're. You're - shut up, okay?"

"I'm the Doctor!" announces the Doctor in order to relieve some of the tension that's building between Sherlock and Sam, who glare at each other across the room. Rose wonders who'd win in a fight. "I'm 905, I'm from the planet Gallifrey, and I know a lot about aliens, if that helps at all."

"It doesn't," says Sherlock.

"Hold up, aliens?" Dean cries, along with John's cry of "what the Hell?"

"Dean, you know very well that there are other planets out there," Cas tells him quietly. "Death told you."

"What's going on," John breathes, running a hand through his hair.

"Okay, well, this is definitely a demon," Sam tells the Doctor. "Sorry, man."

"Oh, don't be. This is all very exciting." He's still grinning, and Rose admires his calm. She'd never say anything, but she's freaking out inside. Aliens she could handle. Werewolves, too, even if they _were_ in the royal family. But demons? _Vampires?_ It's a miracle she's still alive. It's a miracle _anyone_ is still alive.

"Wait, Doctor?" Dean frowns.

"That's me."

"Doctor what?"

"No, you did it wrong."

"What?"

"You have to say 'doctor who?'"

" _Why?_ "

"Just do it."

"...doctor who?"

"Just the Doctor!" He holds out a hand for Dean to shake, which he does, because he can't think of a comeback. Also he's probably worried that the Doctor might start breathing fire or something, as Rose had been when she'd first found out he was an alien.

"Is it my turn?" Rose asks. No one replies, so she says, "Right then. I'm Rose Tyler, I'm nineteen, I travel with the Doctor. Not much to say, uh - I used to work in a shop?" She lets out a nervous laugh. Everyone is staring at her. It's awkward. "Someone else go, please."

"I'll go," John says, shooting her a warm glance. "I'm Dr. John Watson. Sherlock and I solve crimes, but I was an army doctor in the 5th Northumberland Fusilier."

"Oh, nice. Our dad was in the Marines," Sam tells him, smiling. John nods in reply. Dean coughs.

"I'm Sherlock Holmes," says Sherlock, looking bored, though his eyes suggest differently. "I'm a consulting detective, the only one in the world. I invented the term."

Literally everyone else rolls their eyes.

"As I tried to say earlier, we should scout the area," Dean says. "What does this place look like from the outside? Big?"

"Moderately," replies Sherlock.

"We might be here for a while," says John, "we should look for food, water, and maybe a first aid kit."

"Why do you say that?" says Rose, worry creeping into her voice.

"What do you mean?"

"When you say we might need a first aid kit it makes it sound like you're _suggesting_ something."

"I didn't mean anything by it," John says, holding his hands in front of him in a reassuring gesture, which she ignores. "It's just my instinct as a doctor."

"What if it's in him again?" Sam asks, looking at Sherlock. "Is that usual for him?"

"Sadly, yes," Sherlock answers. John punches him in the arm.

"Okay, right," Rose says loudly, because _someone_ has to take charge, and Dean, Sam and Cas are just talking quietly to each other at the moment. "Doctor, you go with John. Sherlock go with Sam, and I'll go with Dean and Cas."

"Why split us up?" the Doctor asks, turning to her. "We work pretty well together."

She cocks an eyebrow. " _Pretty_ well?"

"I was being modest. We're the best."

"Better. And you heard what the demon said, it wants us in pairs. In _assigned_ pairs. Better to mix it up."

"Very nice," says Sherlock, looking a little impressed.

"Logic, yeah, thought you'd like that." She smiles. He doesn't return it, but nods slightly, which is kind of like the same thing, right?

Dean breaks off his conversation, turning to the rest and saying, "So me and Cas with blondie, Sam with the alien?"

"No, Sam with Sherlock," Rose replies, pointing to Sherlock.

"I thought he was an alien."

"No, I'm the alien," says the Doctor, waving.

"Sherlock's just a genius," John tells Dean in a world-weary tone.

Dean nods. "Message received."

"And please don't call me blondie," Rose sighs.

"Message _also_ received. Meet back in that room -" he points to a door behind Rose, opposite the door they'd entered through "- in fifteen minutes. If you're not back here in twenty, we'll lock the door, because whatever got you, chance is it's gonna go after us too."

"Nice to know our fearless leader is also merciless," John says, leading to a small smirk from Sherlock that he doesn't let John see.

"Hey, we're playing that thing at its own game. If there's one thing I know about demons, it's that you gotta give as good as you get, or all you get is dead." He turns to Sam and Cas. "That all sound good?"

They nod, Sam adding, "Be careful," to which Dean snorts and slaps his shoulder.

Rose sighs, looking at the side of the Doctor's face. He notices, and turns to smile reassuringly at her.

She reckons it's gonna be a long day.


	3. The Song Remains The Same

"So, John, how are you coping with the news?"

They pick their way along the corridor slowly, the Doctor holding his screwdriver out in front of him. It emits a blue light and a creepy sound that makes John feel on edge.

"What do you mean?" John replies.

"You know, the whole 'aliens and demons exist run and hide in a cupboard' bomb that was just dropped. How you doing?"

"Oh. I'm okay. I think I'm doing pretty well, considering."

"Really? Cos your eyes are screaming."

John laughs nervously, his jumper starting to itch around his neck. "Yeah, well. Internally I'm freaking out, but I think I'm doing well overall."

The Doctor slaps him on the back roughly. It's meant to be friendly, but it shocks John more than anything else. "You'll be fine. It takes some getting used to, but it's nothing to be scared of in the end."

"Right." They walk in silence for a minute or so before John comments, "Sherlock seems to be doing okay, though, which helps. It's when he gets scared that something's _really_ wrong."

John feels the Doctor look at him for a few moments while he avoids his eye. Then he says, "Why do you hang out with him, anyway?" John looks at him in surprise, so the Doctor continues. "Well, I just mean, what's in it for you?"

If he had a quid for every time he'd been asked something like this over the past year or so he wouldn't have to take weekend shifts at the surgery. He gives the answer he always gives: "I don't think that's any of your business."

The Doctor raises his eyebrows, smirking. "Oh. That's fine. Sorry. Trust issues." He grins again. "I'll get that sorted, don't worry. You'll love me by tomorrow."

"Whatever you say, mate." He highly doubts this. It'd taken a special case for John to be, as Mycroft had said, 'very loyal very quickly.'

He walks slightly behind the Doctor, not from choice, but due to the man's seemingly limitless amount of energy. Observing him, John notes the muddy trainers, worn suit, and the brown jacket folded over his arm. _What is it with geniuses and big coats?_ he thinks, mouth setting into a line. _Maybe I should get one. No, but then I'd look like I was copying Sherlock. Also too short. I hate being famous._

They find a cupboard and wander into it. The Doctor goes straight to the broom, complaining about his screwdriver "not doing wood" or something, while John's eyes immediately flick to the red cross of a first aid kit.

"Hello," he says in surprise, picking it off the top shelf. "Look here."

The Doctor turns and cries, "Brilliant! Should we head back?"

John checks his watch. "We've got three minutes, so yeah, probably."

"This was fun, eh? We should do it again some time."

John doesn't reply, just sighs and walks away, seriously considering locking the Doctor in the cupboard.

* * *

Of all the routes, of _course_ Sherlock chose the most complicated. Friggin' _typical._

He keeps up a running commentary of deductions as they walk, and Sam rolls his eyes with every unnecessary mention of soil or fungus or something that goes right over Sam's head. Sherlock's got his coat collar pulled up again, and his facial features are as sharp as his manner. Sam hates them both.

"What was her name?" Sherlock says suddenly, turning to Sam with his eyes narrowed.

"What?"

"The girlfriend that died ten years ago. What was her name?"

Sam clenches his fists, thinking _don't hit him don't hit him don't hit him_ while counting to ten in his head. "It, uh. Seven years."

"Oh, my mistake." He waits with his eyebrows raised, like Sam's _seriously_ going to answer that question.

"How did you know?" says Sam, voice still angry, but with a dash of defeat in there too.

"Frown lines," Sherlock dismisses with a wave of his hand. "They're like the rings of a tree trunk regarding emotional trauma."

Sam nods once tightly. "Do you see this kind of stuff in your head all the time?" He's curious, even if he wants to smother Sherlock in that stupid coat of his.

"Yes."

"Do you ever want to, you know. Not?"

A blank look from Sherlock. A deep breath by Sam.

"Do you ever want it to like, switch off?"

The taken-aback look on Sherlock's face convinces Sam that no one's ever asked him this before. He takes a few moments to think before saying, "Sometimes it gets frustrating when I don't have anything to direct my processes towards. But most of the time I'm glad it's there." Brief pause. "I get bored a lot, though."

"Okay, cool. Cool." He keeps walking casually, smiling as he does, pleased at how uncomfortable he managed to make the detective. It's not like he's a mean person but, hey. At least he didn't gank the guy.

Sherlock lags behind this time, probably because he knows he'd have to jog if he wanted to catch up with Sam now. Sam sticks his hands in his pockets and whistles gleefully. This is really not the worst situation he's been in in the past month.

* * *

_The lights go out. I change._

* * *

"Shit!" Sam yells, looking around himself desperately. "We don't even know who it was in last time!"

"Wasn't me," Sherlock mutters. "I guess we'll find out when we regroup."

Sam just nods. They've reached a dead end and found nothing on the way.

"So, your parents are dead –"

"Okay how about you shut up."

"Fine."

* * *

When the lights come back on the Doctor is lying on the floor and John helps him up, withholding his panic until he knows for sure. "Was it in you?"

The Doctor nods, running both hands through his hair. "Yep."

"Are you okay?"

"Yeah, yeah, I'm fine."

"What was it like?"

"Horrible. Come on, we have to get back." He walks off before John can say anything else.

* * *

It's something about his walk, Dean notices. It's like he's deflated a little.

He watches Cas make his way down the hallway like it's the green mile, head constantly turning left and right like he's freaking _scanning_ the place or something. His hands are clenched by his sides, knuckles white. Usually he'd be looser – stiff, yes, but loose, using his body as a vehicle instead of using it to show his emotion. It's weird when Cas is like this. It makes Dean worry.

"So what do you turn into?" he hears Rose say. He'd kind of forgotten she was there, walking quietly beside him.

"What?"

"You know. Vampire? Angel?" She chuckles. " _Ood?_ "

"The hell is an ood?"

"They're just ood."

"Was that a pun?"

"I'm not sure."

Dean feels like Rose is making fun of him for some reason but he's not sure.

"No," he sighs, "I'm not a vampire. At least, not anymore."

"Do I want to ask?"

"If you want a gross story, then yeah."

"I don't want to ask."

He smirks, turning to her. "Nah, I'm all human, baby." He winks.

His head snaps up as he hears a sigh come from Cas and realises he's stopped walking and is facing them. Cas rolls his eyes, a petulantly human gesture. "I've found something," he says, and Dean fully understands the implied ' _if you've quite finished'_.

"Awesome, what you got?"

Instead of replying, Cas opens the door in front of them. There's nothing inside.

"Well, good job, Cas. Gold star to you for a friggin' empty room."

"Oi, I'm sure there's something else," Rose says.

"Thank you." Cas shuts the door. "If you have _patience_ I can show you what's strange about this."

Dean doesn't reply, making his silence Cas's cue. Cas then mutters a few words in Enochian and reopens the door. It's now filled with all kinds of stuff, but Dean's eyes go straight to the food lining the walls.

"Yes please," he says, excitement lighting up his face like it's Christmas and he's ten and he actually has presents. He swans in and starts looking around gleefully, slapping Cas on the shoulder and saying, "Nice work," as he passes.

"What was that?" Rose asks Cas while Dean is parading around like a bull in a bull-food store.

"Enochian, it's the language of angels," Cas tells her, looking at Dean all the time he does. "Not many demons speak it. I assume it was used to keep other demons out."

"But it's so easy for angels to get in."

"We don't usually do things like this. We're more 'big picture' matters."

"What, like the apocalypse?" Rose jokes, nudging him with her elbow.

His face darkens. "Yes, that was a troubling experience."

She stares at him. "You're joking me."

"It was very serious."

"I don't – okay, I wanna hear more about this later, definitely."

Cas is still staring at Dean as he loads his arms with food, repeatedly swapping something out for something else that he likes better.

"Does he know?" Rose asks quietly, watching Dean too now.

"Know what?"

"How you feel about him."

Cas's face flushes pink and his eyes widen in something not too far from fear. "I don't know what you, uh, mean – I, we're colleagues. Friends. Good friends."

"I know, I know that."

There's a silence for a few moments.

"How did you know?"

"Oh, it's easy. It's the way you look at him. It's like... he's your centre of gravity."

Cas nods once, takes a quiet deep breath.

"No," he says after another pause, "he doesn't. And I'd like to keep it that way."

"I won't say anything. But, you know. You were possessed, so the _demon_ knows."

"I don't think it does. I'm the most powerful one here, it wasn't built to possess me. It's unlikely the memory integration was very detailed. I doubt it knows my emotions." Pause. "I wasn't designed with them, they're not meant to exist." He thinks for a few moments. "It wouldn't make much difference if it knew, anyway. Whatever happens, I know that I'll fight and die for Dean."

He doesn't wait for Rose's reply, just walks into the room to help Dean carry the food. Rose sighs, leaning against the doorframe for a few seconds before following.

* * *

The room's nicer than the hallway, with some chairs and a window. It's blacked out, but it's still a nice feature. Adds depth to the whole ordeal.

John and the Doctor are the first ones back; the Doctor scans the room while John rifles through the first aid kit, muttering, "Bloody useless," as he finds plasters and smiley-face stickers. "Is he messing with us?" John says loudly, looking up to the Doctor, who replies, "Isn't that the point of this?"

He's right, but John's still pissed off. He'd feel a lot better if he wasn't worrying about someone bleeding to death. He watches the Doctor for a moment, a bit wary since he found out the Doctor had been possessed for the first part of their little trip. It'd been horrible to find out he'd been talking to the demon the whole time and had absolutely no idea that he was. It really brought home the idea that they were under this thing's power, completely. He hopes someone finds some tea.

Dean, Cas, and Rose come back next, with Dean grinning and yelling "they have pie!" and all their arms overflowing with packaged goods. They dump their stuff in the middle of the room, next to John's feeble and rather insulting first aid kit, and stand in a circle around it.

"No chips," Rose comments to the Doctor.

"I knew my hopes were futile."

"Don't give up. Crazier things have happened today than finding fresh chips in an old warehouse or whatever this place is."

No tea, John observes sadly. Ah well. Probably would have been weak, anyway, just to make him mad.

Sherlock and Sam return last, empty handed and tense. "Oh great," says Sherlock, seeing the pile in the middle, "we're the only ones who didn't bring anything back."

"Maybe because you were talking about the emotional meaning behind my hair the whole time," Sam snaps, going to stand next to Dean. They share a nod.

"Maybe because you kept hitting your head on the light fixtures." He stands next to John, eyeing the food, then points to something. "What's that?"

John follows his eyeline to see a black box that certainly wasn't there before. "Oh, god," he says in surprise.

Dean looks at it, frowning. "I did _not_ pick that up. Cas? You pick that up?" Cas shakes his head. "Rose?"

"No way. Too creepy, I would have remembered." She moves forwards and picks it up. "There's nothing written on it."

"Be careful with that," warns Sam. "It could be cursed."

"Well I'm touching it, and I'm fine," she dismisses, in the same way one would respond to a mother telling you to take two jackets.

The box opens easily in her hands. Her face remains calm as she searches through the contents with her fingers briefly before pulling out some white envelopes. "Ooh, what's this," she says to herself, putting down the box and flicking through the envelopes. "Seven," she announces.

"One for each of us," Sherlock says.

"Well that's encouraging," Dean mutters.

"They have our names on them," says Rose. She picks out Sam's one, turning to him. "You mind?"

"Go ahead," says Sam immediately, before realising what he's said. John watches the hesitance and discomfort shift over his face before settling on mild concern.

Rose opens the envelope, sliding out a white card. She skims it quickly before reading it aloud. " _Sam Winchester, 29. Clowns. Letting Dean down. Going back to Hell._ " She looks up again. "It goes on."

"You don't have to, uh, read it all," he says, before taking the card from her and turning the contents away from his brother.

"Dean, here's yours." She gives him a questioning look, and he answers it by taking the sealed envelope from her and opening it privately. Rose takes the hint and gives them out to everyone before receding back to the circle next to the Doctor. John notices that the Doctor doesn't open his, just slides it into his inside pocket and crosses his arms over his chest.

John opens his. He reads it, reseals the envelope, and slips it into his jacket pocket. He glances over to Sherlock and is surprised to see he's gone white as the paper he's still staring at.

"What's on yours?" John asks conversationally.

"Nothing. I don't have any fears, you know that." His voice is stiff. It's very obvious that he's lying.

"Let me see it then."

"Let me see yours."

They stare each other down before it's obvious that neither will give up the information, at which point John purses his lips and turns away. He catches Sherlock's smirk in his peripheral.

"It's our fears," says Dean suddenly. "It knows our fears."

"How?" Sam asks.

"I don't know, do I?"

"Is it gonna use them against us somehow? Like, get a giant clown to chase me around the building?"

"That would be hilarious," murmurs Sherlock, and Sam's face becomes the pinnacle of suppressed bloodlust.

"I don't think so," says Cas in a gravelly voice, commanding everyone's attention immediately. "I think it's a power play. It's informing us that it knows all this, that it knows a lot about us, and we should be afraid." He deliberates for a moment before continuing, his voice deeper than before. "I don't think a clown will chase you, Sam, but it's possible that one of each of our fears will be exploited. It's targeting our _deepest_ fears. It means to pick us off one by one."

There's a dramatic, overflowing silence, until Sherlock says, "Well, isn't _that_ inspired."

"Hold on, I thought it was gonna do pairs or something?" John asks.

"No, the pairs don't work now they brought the angel," Sherlock tells him.

"His name is Cas," Rose says, slightly irritated. Sherlock rolls his eyes.

"How does it know so much about us?" cries Dean, looking around himself, probably for a table to knock stuff off.

"Oh, I know all of you," says Rose. A smile builds in the line of her mouth.

Cas grows pale.

"Shit," Dean mutters. "You really had me going, there."

"Oh, please, it was easy. She's really very simple."

"Don't you dare," threatens the Doctor, pointing to her in anger. "Get out of her, now."

"Or what, old man?"

"Or I swear, I won't give you a second chance."

"But you're so famous for your _mercy._ "

"Not today. Not with you. Not with Rose."

No new emotion crosses Rose's face, but the thing inside her would be a fool not to be scared. If someone looked at John that way he'd probably go straight for his gun.

Rose nods and says, "Noted," before walking away from the Doctor, passing around the perimeter of the circle they've formed around the food. "I wouldn't eat that food if I were you," she whispers in Dean's ear, "it's been there for eighteen years." He looks thoroughly disappointed.

"So was Cas right?" says Sam, his voice tight. "Are you gonna get us through our deepest fears?"

Rose shrugs. "Maybe…"

"That's a yes."

"Okay, yeah, I am," she yells suddenly, waving her arms about. "You got a problem with that?"

Sam's jaw flexes. "Yeah, I'd say I do."

Rose rolls her eyes, turning them black in the process. "So needlessly defiant. If you play along you'll all be _fine_."

"You mean that?"

"Of course not, who do you think I am, Mother bloody Teresa _?_ "

"Why are you doing this?" Sherlock interrupts in the voice John recognises as meaning _I'm gonna deduce the hell out of you and you can't stop me._

Rose comes up behind him, grabbing the spaces between his neck and shoulders in both hands, and leans in close to his ear. He winces slightly.

"Tut tut, Mr Holmes," she breathes. "You're not the only one who gets bored."

* * *

_The lights go off. I get to work._


	4. Black Dog

"You son of a bitch, where are you?" Dean threatens, looking around them all.

"For all we know, it's in you," says Sam quietly, and Dean stops and re-evaluates, changing tactic.

"Right. We gotta get as far away from each other as possible."

"And why's that?" asks John.

"That thing is gonna play on our _fears._ That means scary crap running around all over the place. You really want seven monsters in this tiny room with us?"

"But if we split up we won't be able to defend ourselves as well."

"Oh yeah? Where'd you get that from?"

"Afghanistan," John replies coolly.

"Right, well, that's great and all, but these aren't people. These are your nightmares."

"You're thinking too rationally," Sherlock says, and John is so surprised that he snorts. "It's _fears,_ not monsters. They won't all be zombies and vampires. I don't see how 'letting Dean down' is gonna run in here, guns blazing."

Sam looks self consciously around him.

"I still think should stick together," John says.

"I still think we should split up," Dean replies, and John narrows his eyes.

"Let's take a vote," the Doctor interrupts, stepping forwards to relieve the tension. "Raise your hand if you think we should split up."

Sam, Dean, Cas, and Sherlock raise their hands.

"Right, that's settled. Let's stick with who we know this time. Sammy, Cas, come on." Dean walks out of the room, the others following.

John sighs. Arrogant Americans have been plaguing him his whole life. Now he just might die because of one. "Where are they even going?"

"Probably to the best defensive position," Sherlock replies. "John, we should be doing the same. Although, they probably have a different definition of _defensive."_

"What's _your_ definition?"

Sherlock smiles, and it makes John worried. "You'll see. Trust me."

* * *

Dean hunts in the store room for salt, Sam for oil, while Cas keeps a lookout at the door. He's doing a pretty bad job, though, seeing as he's just looking at Dean the whole time. His reflexes are faultless, though. He's not putting them in danger. He'd never do that.

He notices that Sam keeps looking over his shoulder. Maybe Sherlock's jab about a giant clown had actually put him on edge. He supposes that's the idea of all of this, to put them on edge. Why else call the fears to attention? Why not make them just appear?

To make them afraid. The fear of fear is more powerful than fear itself.

"Nothing," says Dean after a few minutes, throwing a bag of flour on the floor in exasperation. "This guy knows his stuff."

"It's not like a demon would leave weapons around and then trap us in with them," Sam says, rolling his eyes. "I told you this was pointless."

"Oh, well, good for you. We've lost time. We have to seal ourselves in here."

"Here?" Sam asks in surprise, eyebrows shooting up. "This is your defensive position? The friggin' storage room?"

Dean points to the door, towards Cas, who smiles at him, but he doesn't see. "One door. No humans can get in, cos they don't know Enochian. No windows. A lot of stuff to grab and hit something with."

Sam sighs. "Fine. Don't blame me if that thing cracks an egg on your head."

They start painting demon traps with pink icing at Cas's feet. He averts his eyes.

"Hey, Cas, wanna help?" Dean asks, looking up.

"I'm keeping watch."

"I think we got it covered, seeing as we're right here."

"Oh. Alright." He grabs a pot from Dean and starts smearing the icing across the floor. "I don't think this will work."

"Yeah, well, it's all we've got. It's worth trying. It's always worth trying."

Cas sets his mouth in a line.

Suddenly Sam whips his head around and stands up, hands out ready to fight. "What?" he cries, looking around frantically. "I saw – _what?_ "

"What's up?" Dean asks, standing too. Cas follows suit.

"Nothing... nothing. Nothing." Sam frowns and squats back down to continue working.

"Is it getting to you?" Dean asks quietly, probably not meaning for Cas to hear, but he's a celestial being, of course he's going to hear.

Sam takes a deep breath, and exhales sharply. "I don't know. Maybe."

"Keep your cool, okay? Wanna go lie down or something?"

"Shut up. I'm fine."

But it happens again, Sam whirling around so sharply he almost falls. This time, he agrees to take it easy for a few minutes. He takes the plank of wood Dean had ripped from a table and goes to sit in the corner.

"Do you really think that's a good idea, leaving him alone?" Cas asks, stopping his work to look at Dean.

"Trust me, Sammy's so embarrassed about the clown thing that he'd rather _none_ of us were here."

Cas doesn't think this sounds like Sam at all, but Dean knows him better than he does, so he trusts him and nods.

They finish the makeshift trap and stand up. Dean wipes his hands on his jeans. Cas cleans them both up with his Grace.

Cas starts to walk towards where Sam was headed, but Dean puts out a hand to stop him. His fingers close around Cas's bicep. Cas finds himself leaning into it.

He turns around. "Dean?"

Dean lets go slowly, lingering a little. "Uh, I wanted to ask. What were you and Rose talking about earlier?"

His insides tighten. "Why?"

"I wanna make sure she's not keeping anything from us, or anyone is."

"Well, she was the demon at the time, so I don't think it matters."

"What did she say?"

"Nothing of importance."

Dean sighs, rubbing the back of his neck. "Cas, I heard what you guys were talking about."

"You -"

"Yeah."

"Oh."

There's a silence that's too empty and too full.

"I wanted to say..." Dean crosses his arms across his chest, and then puts them back by his sides. "Uh, damnit. How do I. Okay."

It's happening, Cas thinks, he's rejecting me. He closes his eyes and makes his peace with it.

Then he feels hands on his hips and a warm presence in front of him and he opens his eyes to see Dean right in front of him, looking right in his eye, obviously freaking out but still smiling a little.

"Uh, I guess I wanted to say, I feel the same way."

He can't be sure, because there are no windows in this place, but Cas is pretty sure that the sun just came out. He bathes in the warmth, the solidarity, the assuredness. It's summer. It's bright. He smiles.

But then he remembers where they are.

"How do I know you're not the demon?" blurts Cas, and immediately feels terrible for even thinking it.

Dean frowns, his grip on Cas loosening a bit. "What makes you say that?"

"This all seems too good to be true."

Dean laughs, smirking slightly, and his eyes are like the sun, too, but Cas could look at them all day. "Right. Tell you what. You look into my eyes and tell me I'm not me."

So Cas looks. They're not black, that's for sure. They're Dean's eyes. They're all crinkled up at the sides because Dean has started smiling again. They're so green, like the grass in his favourite Heaven, the eternal Tuesday afternoon, and he can't remember what day it is, but he wants to spend them all with Dean, all the Tuesdays and Wednesdays and Thursdays and all of his days, why is he doing this just let me -

He breathes out slowly through his nose as ice water makes its way through his veins.

He's noticed something. He can't place what it is, but it's there, and he knows it.

"You're not you."

Dean's hands fall from Cas's waist, pulled away by the strength of the demon's laughter. Cas stands still and watches the thing, how its body convulses unnaturally when it laughs, how its eyes are open the whole time, black now, staring right at Cas.

The demon wipes its eyes, smiling. "Wow, you got me! You really do love this guy, huh?" The British accent is back. It scoffs. "Don't know why, it's only self loathing and thoughts of suicide in this mother." It raps its knuckles against Dean's head. "Not much about you, though."

"Let him go," Cas tells it, strangely calm, probably due to the mixture of sorrow and anger, both weighing him down so heavily he can barely move.

"You sure? Cos, you know, he's gonna remember all of this."

Cas digs his fingernails into his palm to repress the lump growing in his throat. "Let him go."

"Okay, fine. So, uh. Deal with _that_ problem immediately." It winks, the one eye turning back to Dean's.

* * *

_The lights go off. I change._

* * *

"Dean, are you alright?" Cas asks him, pulling him to his feet.

Dean looks weak, but not harmed. In fact, he's gone red in the face; from anger or embarrassment, Cas can't tell, but they're both definitely there. "Where the fuck is it," Dean breathes, so quiet and threatening that Cas wants to give him answers he doesn't have.

"We can't tell."

"Where is that son of a fucking _bitch?!"_ Dean yells, striding away from Cas, whose hand falls from Dean's arm. He runs after Dean, calling his name, but Dean's fast, searching every room he passes for the demon without stopping.

He knows it's futile. Cas knows he knows. That makes it a little bit worse.

"Dean, it's no use," Cas says quietly when Dean reaches a dead end and faces it, breathing heavily, balling and unballing his fists. He can't see Dean's face, and he doesn't want to, because he's scared.

It's then that he realises. His fears. He's been exploited.

Dean punches the wall in front of him and turns around, bumping into Cas on the way past with his shoulder. Cas doesn't look at him. He's afraid. He'd been afraid before, he's afraid now, and he's afraid of what's coming.

Well played, he thinks.

"Listen here, you bastard!" Cas hears Dean yell, and turns towards the sound. He can't see Dean anywhere. He must be round the corner, and shouting really, really loudly. "I swear to God I am going to get you. I don't give a shit how long it takes, buddy, I've got no commitments. I've dealt with worse than you, and I will do again. You wanna make us afraid? Huh? Well you're not gonna. You know why?" There's a loud bang. Dean probably threw something. "We're the ones you should be fuckin' afraid of."

A door slams.

Cas takes as deep a breath as he can, holding the air in his lungs for as long as he can before it starts to burn and he lets it out all at once, head spinning, and repeats. He does this for a few minutes before walking towards Dean's voice.

* * *

"I'm not locking myself in there."

"I'll be there too."

"That's even worse."

"It's by far the best defensive position."

"Sherlock, for God's - ! I'm not locking myself in a bloody broom cupboard with you!"

Sherlock sighs. "Stop being childish. Do you want to die?"

John doesn't dignify that with a response.

"I don't see why you don't trust me."

"I _trust_ you, sure. I just, would rather not be in a confined space right now, given the circumstances," John says slowly.

Sherlock rolls his eyes. "Oh, what you think I'm the demon?"

"You couldn't tell when it was in _me."_

"Yes, but. This is about protecting ourselves." He frowns, and it has a dash of pout in there too that John doesn't like the look of. "Please."

John looks at him for a few seconds, then eyes the cupboard. There's about one and a half metres squared of floor space, not to mention the actual bucket and mop in the corner, and the faint scent of either strong chemicals or a dead body.

But this is Sherlock. When has he ever been wrong?

John groans. "The things I do for you," he mutters, pushing past Sherlock to stand in the cupboard. Sherlock nods once, following him in and shutting the door behind him. He locks it.

"It's very dark," John comments.

"That's in our favour."

"Why? The thing can probably see in the dark."

"...oh."

"Please turn the light on."

"Fine."

John flinches as the bulb lights up the room around him, illuminating Sherlock's face. It's very close.

"This is a bit intimate."

"Sorry," Sherlock replies, trying his best to stay out of John's personal space, while being unaware of the concept. John appreciates the effort, though.

And then there's not much to do but wait.

"Why won't you show me your fears?" John asks quietly after about ten minutes, because it's been bugging him like mad for ages.

"Why won't you show me yours?"

"Yeah, but that's different. It's logical for me to know your fears. Like, if you're afraid of spiders, I don't go buying you a tarantula for Christmas."

"Oh, I'd love that -"

"Oi."

Sherlock rolls his eyes for the millionth time today. "I thought you of all people would respect boundaries, John."

John raises his eyebrows. "You don't seem to respect mine very much."

"Exactly. Now you know the value of them."

"You don't think they exist!"

"That's true, I didn't." He pauses. John sees trains of thought pass over his face. "I didn't think I had any fears. But this creature, demon, whatever, has them spot on. And I find it's not information I'd like to share."

John nods. "That's alright, then." He's just glad to see some actual human behaviour coming from the man.

He keeps his posture like an army man, shoulders back, head upright, because there isn't space to sit down, and they're gonna be here for a while, so he may as well get comfortable. The air is cold, so he wraps his arms across his chest, rubbing his hands up and down his biceps. Sherlock glances down at this, and fidgets inside his big coat. He's probably not cold at all, John thinks. What a bastard.

"Are you cold?" Sherlock asks. This confuses John, because even if you're not Sherlock Holmes, it's pretty obvious that when a person is rubbing their arms it means they're cold. Oh, right. It's more of a social cue. Sherlock's asking whether John wants his coat.

"Nah, it's alright," John replies, feigning nonchalance, waving it off with a hand.

The air keeps getting colder, he notices. It puts him on edge. But Sherlock doesn't seem to notice.

Eventually John starts shivering, sticking his hands into the pockets of his jeans. "Christ, if this thing is from Hell, why is it so damn cold in here?"

"I don't feel anything."

"It's that bloody coat."

"No, really." Sherlock takes off his coat, waits a few moments, slips it back on, and says, "I don't feel anything. Do you have any fears to do with the cold?"

John steps backwards, banging into the bucket with his heel. "No. _No._ Why'd you say that?"

"If you're feeling it and I'm not, it could be one of your fears being exploited." He's so calm, John wonders how that's possible.

"I don't have any fears about the cold," he blurts, assuring himself more than Sherlock. It's true, though. He doesn't fear freezing to death more than the next guy. But the temperature is dropping rapidly. He starts jogging a little on the spot to maintain some heat.

"Is that the truth?"

"Yes!"

Sherlock thinks for a moment, and John almost hits him out of impatience. "It's probably just a scare tactic. Hmm. I wonder how this is possible. From what the Americans said, it sounds like demons shouldn't be this powerful."

"Oh yeah, cos you know so much about d-demons," John snaps, growing more irritated as his toes go numb. His teeth start to chatter. "C-can we g-get out of this b-b-bloody cupboard now?"

"Well really, we should stay, so my body heat can warm you up -"

"SHERLOCK!"

"Fine, fine." He turns around slowly, gripping the metal handle and pushing down. It doesn't move.

"I can't get the door open."

"You're kidding."

"It's locked us in."

"I'm going to kill something. I swear to God, I'm going to kill something."

Sherlock shuffles back around in the cramped space that seems so much smaller now. "I bloody _told_ you this was a terrible idea," mutters John, to which Sherlock rolls his eyes, again, but John doesn't mind as much now, because at least they're not black.

Then the lights go off.

Sherlock and John squint at each other in the sudden light.

"Was it in you?" Sherlock asks warily.

"No, you?"

"No."

"Good." Pause. "Is it in you now?"

"Not to my knowledge."

"Me neither."

"One of us could be lying."

"Yeah, I know."

John starts jumping up and down with the cold, so Sherlock removes his coat and hands it over with no emotion on his face. "Here."

Normally John would decline again, but he's starting to lose feeling in some important places, and Sherlock's apparently fine, so he takes the coat with a quiet "cheers" and puts it on, sighing at how long it is on him, but also at how warm it is and how heavy the fabric is and how deep the pockets are. He's starting to understand why Sherlock wears the thing all the time. It's a nice flippin' coat.

"Any better?" Sherlock asks.

"Yeah, thanks." Really, he's just as cold, but the thing's so damn _comfortable_.

He's also more than a little bit afraid. But he's not gonna tell anyone that. Hell, he doesn't even want to admit it to _himself._

It seems the games have begun.

* * *

"So, uh," says Rose once everyone's run off somewhere. "What do we do?"

The Doctor pulls out his sonic screwdriver and fiddles with a few things, pointing it up and turning in a circle. "C'mon c'mon c'mon," he whispers under his breath.

"What are you doing?"

"I'm trying to get a signal from the TARDIS."

"What for?"

"If I can get into the main frame, I might be able to do a full scan of this place... I think the signal's blocked, though."

"Doesn't _look_ like there's any alien tech around."

"You never know." He sighs and pockets the sonic. "Well, I'm a bit useless."

"You've still got that big Time Lord brain of yours," Rose says, nudging him with her elbow. "May as well put it to a good cause."

"What are you getting at?"

She looks pointedly at the pile of the food in the middle of the room. "Is there any of that we can eat?"

He rolls his eyes, but picks her up a can of something. "Here."

"What is it?"

"God knows. Take a chance."

She resists the urge to throw it at him.

"No, but seriously." She puts the tin on the ground and looks around. "Shouldn't we be hiding or something?"

"No point, really. This thing can walk through walls and stuff. No reason it couldn't find us hiding in a cupboard."

"Yeah, but we gotta defend ourselves against him. We can't really do it in a huge room like this."

"More room to run." He jogs on the spot for a moment, grinning.

"Running's what you do best, isn't it, Doctor?" Her voice is cold, and he stops, frowning.

"Well, I do a lot of things very well."

"Running from every problem, all your life." She shakes her head, disappointed. "You fix tiny planets, insignificant civilisations, but it's nothing compared to the destruction you've caused."

"Rose, what are you doing?" He takes a step back. "Is it you? Are you the demon?"

She laughs. "Such arrogance, assuming that I have to be some kind of _creature,_ some kind of _abomination,_ in order to question you."

"I didn't mean that -"

"Tell me what really happened on Gallifrey."

It feels like a blow to the stomach; all the wind rushes out of him. "You know what happened. There was a war. I fought on the front line."

"At first, yes."

"How do you _know_ this?!"

"The demon told me. It's true, isn't it?" He doesn't answer. She shakes her head again, sighing. "I used to idolise you. Love you, even. But there's another side of you, one I haven't seen, one you keep hidden under all those layers of defenses you pretend aren't there." Her face starts to glow as she talks, and the air gets hotter around him. He looks around himself in panic. The ground is starting to glow, too, bright orange, and shapes start to materialise around Rose, buildings, taller than any on Earth, with symbols and structures he hasn't seen in hundreds of years.

"No," he breathes at the sight of Gallifrey burning.

Rose stands in the middle of it, fire at her feet, spreading up her legs. "It's your fault!" she cries, desperate, hoarse, panicked, and screams in pain. He reaches out to her, but the heat is too strong, and he can't do anything, he can't do _anything,_ he's stuck here and if the fire reaches him, if it starts to spread – he's going to have to run again –

"IT'S YOUR FAULT!" Rose screams at him, tears scraping down her face. The flames envelop her whole body. She falls to the floor.

"I'm sorry," he says to nothing, watching everything collapse in front of him and feeling everything collapse inside him and he turns to run and –

Rose is shaking his shoulders and saying "Doctor!" over and over and she slaps his face and holds him upright as he finds that nothing's burning, nothing's falling, she's holding him upright as he cries and shouts at thin air.

"Rose," he whispers. "It – you're okay."

"Of course I'm okay! What happened?" Her eyes are wide, huge and round with concern.

"You... I -" He pulls her into a desperate hug, relief held off by fear, such intense fear that he hasn't felt in a long time: fear of destruction; fear for Rose; fear of her finding out who he really is; fear of her leaving once she does.

She strokes his hair and rubs his back and whispers "it's okay" in his ear and he doesn't want to let her go, but he knows that eventually, he'll have to.

* * *

Sam sits with his back to the corner of the room, clutching the board of wood to his chest and staring, wide eyed, at the space in front of him. He knows it wasn't possible that he'd seen what he'd seen. Of course it's just the demon messing with him. That man hasn't been in this plane of existence in a long time. He's gone. He can't come back.

But Sam still saw him, and he's still afraid.

After ten minutes or so, the lights go off, and he raises the board, trying to defend himself somehow. He can feel the cool stone wall behind him, which suddenly seems so much cooler that it starts to burn him, so he stands up, ready to run if necessary. He doesn't know where Dean is, or Cas. He can't hear them, or see anything at all.

He drops the board and cries out at a burning pain in his chest, over his heart, so intense that he collapses backwards against the wall, hitting his head. It feels like someone is holding a flame to his skin, and his head is going to explode, and he starts to see green fuzz dancing in front of his eyes, and his eyes start to close -

"No, come on, get up, it's over now."

Sam lurches to his feet. Wait, no he doesn't.

"What's going on?" he tries to say, but can't.

"Sorry love, couldn't get past your little tattoo." It's that accent again, the weird, twisted version of English that he can't quite place. "It had to go."

The lights come back on, and he slowly gets to his feet, against his own will.

And then he gets it.

"I'm gonna kill you," he thinks, and the voice in his head laughs.

"I was rather hoping it would be the other way around."

"Get out of me right now or I swear to God -"

His finger goes to his lips. "Shh. Listen."

Dean's voice is echoing down the corridor, swearing and threatening and so loud and angry that Sam wants to help, run to him, but he _can't._

"He's threatening me," thinks the demon, voice blatantly amused. "That's adorable."

"How did you know about me and Dean? We're not even _from_ here!"

"Just call me Nick Fury."

"What?"

"I assembled a team of extraordinary people. So much contrast, I thought it would be fun. A _Battle Royale_ kind of thing."

Sam manages to sigh bitchily inside his own head. "So our lives are your playthings? Do you realise how much damage you're causing?"

"Well of course, that's the point of this. Shut up now. Gotta concentrate. This meat suit of yours needs a lot of coordination."

Sam protests as loudly as he can as he's pushed further and further back in the demon's mind until his shouts are no more than quiet whispers.

"Better," he hears the demon think. Then, out loud, it cries, "Hey, Dean?"


	5. Houses of the Holy

"What is it, Sam?" Dean says as he walks back into the store room, a practically tangible air of 'pissed-off' around him.

"Oh, I was just wondering where you were." Sam slaps Dean on the shoulder, hard but deliberate. "Where did you and Cas go running off to?"

Dean looks away. "Not important." But Sam knows, and holds back a smile at how hurt Dean looks. "You okay? Lights went off."

"I'm fine. Was it in you?"

Hesitant pause. "Yeah." Sam knew this too. Dean's body had been wonderful to possess, all strong and self-hating. Dean pulls down his shirt to show his burnt-off tattoo.

"Oh, man." Sam frowns his trademark frown. "That sucks. Did you at least learn anything about it?"

"Nope. Dude's mind is like a fortress."

Sam looks around himself. "Where's Cas?"

Dean ignores the question, muttering something about having to "make a move" before grabbing the few possessions they still have and striding, without looking back, out the door.

Cas comes wandering in a few moments later, humbled, with his hands in the pockets of his trench coat for the first time that Sam – the _real_ Sam – can remember. He stands quietly by the doorway, saying, "How are you feeling?"

Sam rolls his eyes. "I'm fine, Cas. Dean went off somewhere, I think he went to find the others or something." But Sam knows that Dean went to find the demon, and that he won't manage it.

The finale is coming. Sam flexes his fingers out, then forms a fist and smiles internally.

"Come on, we should find Dean." He brushes past Cas and walks off, resisting the urge to whistle.

* * *

The door to the cupboard is wrenched open and John jumps, peering round Sherlock to see Dean standing there, looking violated. "What are you _doing?_ " Dean asks.

"Protecting ourselves, obviously," says Sherlock as he turns around. "See? We're not dead."

"I'm not dead either, genius. Get out of there."

"I _would_ quite like to leave, Sherlock," says John, rubbing his hands together.

Dean stares at him. "What's wrong with you?"

"Nothing."

"He's cold, and afraid," Sherlock answers, and John scowls, but doesn't complain or argue, for obvious reasons.

"Why are you _cold?_ " Dean asks. "That doesn't seem very scary."

"My current theory is that it's the ambiguity that's meant to be frightening," Sherlock says.

"Oh. Okay, that's pretty good."

"What about you, any fear exploiting on your end?"

Dean swallows. "Yeah. But it's over now."

"Do you know who was possessed?"

"It was me." He looks ashamed. "I couldn't stop it."

"It wasn't your fault," says John, and Dean scoffs.

"I know, I know. I mean, thing burned off my anti-possession tattoo, I couldn't have stopped it. But… being completely powerless like this, being possessed, that was one of my fears. And then it used the fact it was in me to influence Cas's fears, too, and Sam went all crazy seeing things. This thing is powerful, it means business. I don't know how we can stop it, to be honest." He runs a hand through his short hair, looking thoroughly desperate. John wants to say something to help, but he's powerless, too, even more so seeing as he didn't know things like the demon existed until this morning.

"What time is it?" he says suddenly, looking at his watch. It's stuck at 6p.m. "Sherlock, what does yours say?"

Sherlock glances at his and frowns. "It's stuck."

"Mine, too."

"Same here," says Dean. "But it can't be six, we haven't been here for _that_ long."

"Maybe it's a warning," says Sherlock, his voice quiet. "Something will happen at six o'clock."

"But we don't know how far away that is, our watches have stopped."

"Exactly. Fear."

Dean rolls his eyes. "I'm getting really sick and tired of that word."

"Let's go and find the others," John says. "We need to tell them, and check if they're okay. I told you splitting up was a bad idea."

"You want a freakin' cookie?" Dean mumbles, walking away from them.

Sherlock puts out his hand to keep the door open. "You shouldn't take his cookie. That's their word for biscuit. Who knows what kind of thing he'll give you."

"Thanks for the advice." Sherlock walks out and John hurries after him, anxious to leave their cramped surroundings and stretch his legs. He walks alongside Sherlock, feeling the coat that he's still wearing whip around his calves. "So, they're all exploited. I am too. What about you?"

"I think it's pretty clear that I'm not afraid," Sherlock replies in his usual bored tone.

John sighs. "It's really starting to annoy me that you won't tell me what you're afraid of. It's like you're taking the piss."

"How?"

"Well, like, you've always been so impersonal because you supposedly don't have a lot of personal information in the first place, but now there's something and you're refusing to tell me."

Sherlock doesn't reply.

"Look, okay." John takes a deep breath and wraps his arms around himself. "It's not fear itself that I'm fearing, or the ambiguity, or whatever. It's the cold. It's – I think it's because of all the nights I spent on watch in Afghanistan, and it was freezing and I thought I was going to be shot. Alright? Now tell me."

Sherlock glances at him. "No one is going to shoot you."

"Shut up."

"I won't let anything happen to you."

"Thank you, but that's not really up to you."

Sherlock hesitates, and John watches the side of his face, watches his jaw tense. Eventually he relaxes and turns his head away and says, "I'm afraid of something happening to you that's out of my control."

John raises his eyebrows. "What?"

"You're my friend, and that's fine because you aid my deductions and provide companionship, but you're the only person who I've ever permitted to do that. Finding a replacement would be hell." He says the last bit like a joke, and John laughs, but he understands. "Anyway, I'm very bent on protecting you."

"That means a lot to me," John says, laying a hand on Sherlock's shoulder. Sherlock makes an annoyed noise in his throat and walks faster to get away.

* * *

Dean walks in on two figures, huddled up in the corner, clinging onto each other for warmth and for love, and says, "Cut it out."

They stand and Rose glares. "Anything happen?"

"Demon was in me," Dean says, and Rose softens. "All our fears are being exploited. You guys?"

"Same on our end," the Doctor answers. "Where are the others?"

"They'll be here." His voice is gruff and no-nonsense. "We need to get out of this place." Then he explains Sherlock's theory about why their watches have all stopped. Rose and the Doctor check theirs, too – 6p.m.

"That's a bit ominous, isn't it?" says the Doctor.

"That's kind of the point," says Rose, and takes a deep breath. "Okay. I agree. Time to get out."

After a few minutes of waiting, John and Sherlock wander back in – with John smirking and Sherlock thoroughly ignoring it – and soon after, Cas and Sam, who Dean himself ignores. Rose looks around them all and can't see a single smile. Then she looks up at the Doctor and gets one herself.

"Alright," Sherlock says once everyone is in the room. He clasps his hands behind his back and starts pacing. John rolls his eyes. "Here's what we know. One of us in here is the demon. Six of in here aren't the demon. Kindly raise your hand if you are not possessed."

All seven raise their hands.

"Herein lies the problem. We're unable to tell who is possessed. The demon is hearing these words come out of my mouth, but for all you know, it could be the one saying them. It's impossible to tell who is possessed and who isn't."

Cas shifts uncomfortably. Dean tenses his jaw and looks at his feet.

"So, what do we do?" He turns to Dean, Cas, and Sam. "Are there any ways, any at all, that you can think of to show whether someone is possessed?"

Sam shakes his head. "Sorry, man. We don't have the right supplies."

Cas hesitates, then raises his hand. "I may have a suggestion."

"Share it with the class," says Sherlock.

"Well, when Dean was possessed, I assume that his anti-possession tattoo was burned off. Right?" Dean nods, and Cas continues. "So – and I don't mean to offend you here – we can at least tell whether Sam is currently possessed by checking his anti-possession tattoo. If it's burned off, that means he's currently possessed, because he hasn't been in the past."

Sam raises his eyebrows. "Wow, Cas, thanks for the vote of confidence."

Dean narrows his eyes, turning towards Sam. "Hey, Sammy, might as well show them the tattoo. Just to prove your point." His voice is calm.

Sam looks around, sees that everyone is looking at him, and sighs. "I hate detectives."

* * *

_The lights go off._

* * *

Sam opens his eyes, squints at the bright lights, feels strong hands pull him to his feet. He looks around in panic. "Guys, I'm – I was – it was me."

"We know, Sam. It's okay. It's gone now," Dean says from beside him, and drops his hand from Sam's shoulder.

Sam looks around the group. "Did I do anything bad?"

"No, but don't you remember it?" asks John, hands rubbing up and down his biceps.

"I do, I just wanted to make sure." Sam breathes a sigh of relief. "Okay. What's the plan?"

While he waits for Sherlock to think, he tries to ignore the itch behind his eyes. The urge for the true, pure black to be visible. He has to constantly hold it back. It's annoying. But he's deep undercover now. No one thinks it's him. Not even his own brother.

"Sherlock?" John asks after a while, and he sees it, and so does Sam; the great detective is stumped. Sam resists the urge to laugh.

"Give me a minute," says Sherlock, and retreats from his centre-stage position to stand next to John again.

Dean throws up his hands. "This is ridiculous. Let's just kick something."

"That's even _more_ ridiculous," says Sam, with just the right amount of bitchiness to get Dean all riled up.

"Well, genius over there's got nothing, the friggin' _alien_ can't even think of anything, what do you want me to do?" Dean says loudly, shoving Sam in the arm. He turns to Cas. "Any way to contact the Heavenly Host?" He points upwards.

Cas purses his lips. "No, Dean. I've tried."

Dean grunts in frustration and Sam smirks because it's obvious that Dean is mad because Sam had been possessed and Dean hadn't been able to stop it. Dean is clenching and unclenching his fists and his jaw is doing the thing again and he's aggressively not-looking at Cas and Sam is having the time of his life.

And then John Watson collapses.

"John," Sherlock says immediately, kneeling down and taking John's pulse and feeling his temperature and being very clinical about it, because that's his default setting, that's the one he's most used to, and he might change because of John, but John's unconscious at the moment and Sherlock is too panicked to be aware of these things; he's concentrating on the matter at hand.

"Is he alive?" Rose asks nervously.

"Yes, he still has a pulse," Sherlock replies. "It appears he's simply passed out. His heart rate is strong, he should wake up soon."

"What the Hell is going on," Dean says. "Seriously, is he gonna freeze to death?"

Sherlock purses his lips and looks back down at John and doesn't reply.

While everyone is fussing around John, Sam looks at Cas. The angel. The outlier. The one thing Sam hadn't counted on. He'd messed up the plan, thrown a spanner into the works, but you know what? Sam thinks he's handling it pretty well. Cas looks as devastated as the rest of them, if not more so. He's staring at the back of Dean's head, but when Dean turns around, he just looks at the floor, or his hands, or someone else. Unrequited love is a personal favourite of Sam's; perfect for manipulation.

John stirs, and everyone but Sherlock moves back to give him some space, so Sam takes the opportunity to get in close, so close that Sherlock can't see his face, so that Sam is the only thing John sees when he opens his eyes, so the first thing he sees is Sam's black eyes.

"Demon," John breathes, and swings his fist into Sam's face.

It's hardly enough force to harm him, but Sam falls backwards anyway, for effect, and clutches his face. "Ah, dude, what the Hell?" he cries, and scrambles to his feet.

"He's the demon," John says quietly, trying to sit up.

"No, not anymore, we just got it out of me!" Sam says, looking to Dean, who steps forwards.

"It's not in Sam, what are you talking about?" Dean asks, and Sam breathes a sigh of relief. Dean always defends Sam, in practically every memory the real Sam has.

"He had black eyes," John says as Sherlock and the Doctor pull him to his feet, wiping the back of his hand over his forehead to get rid of some of the sweat. "I swear to God he did."

"No, I didn't, I don't do I?" Sam asks, panic in his voice, turning to Dean with his eyes wide, like he's worried. Dean shakes his head in reply.

"It can't be in Sam, that doesn't fit the pattern," says the Doctor. "The demon hasn't possessed anyone twice."

"Is that true?" John asks Sherlock, who nods. "Well, I don't care. It broke the pattern, then. I know what I saw."

"You could be delirious," Cas says. "Maybe you hallucinated it. Maybe this is part of the demon's plan, to make us think that we're seeing black eyes when we're not."

"That's happened to us before, when War came to town," Dean says. "Could this be a horseman?"

"No, the apocalypse is over, that's impossible," replies Cas, and his voice is nervous; not at the situation, but at the fact that Dean is talking to him like everything is normal. "But, this thing is more powerful than it should be. It's possible this could be an extension of its power."

"I'm not crazy," says John firmly, the colour slowly returning to his cheeks. "I'm not. I saw it. I _saw_ it!"

"It doesn't make you crazy if the demon made you hallucinate," the Doctor reassures him. "There has to be an explanation for this."

"You didn't have to _punch_ me," says Sam, peeling his hand off his face and wincing.

"Yes I bloody did, and I'd do it again," John replies, glaring.

"Hey, you stay away from him," Dean says loudly, pointing his finger, stepping in front of Sam.

"Or what? You haven't exactly done much to help."

"Neither have you, unless trailing after your friend over there counts as contributing."

"Stop," says Sherlock, holding up his hand as their voices start to get louder. "There's a perfectly obvious solution."

"And what's that?" asks Dean, voice annoyed.

"It's still in Sam. It never left."

"What?" Sam cries. "That's – what?"

"It's a genius move. Breaking the pattern so no one realises it's still in the same body." Sherlock makes eye contact with Sam and doesn't break it. "It never left Sam. The lights went off, but it didn't change. It lulled us all into a false sense of security. I don't understand why you'd reveal yourself to John, though. None of us would have had any idea otherwise."

Sam lunges forwards, grabs Sherlock by the throat and slams him into the wall. He watches Sherlock's eyes grow wide, hears the shouts from behind him. He leans in close. "I don't care about going undetected," he breathes, staring into Sherlock's eyes, gripping his neck in his fingers. "I don't care if you find out who I am."

"Then what _do_ you care about?" Sherlock says through the choke-hold.

Sam grins, too much, showing all his teeth. "The ga-a-a-ame."

His fingers start to tighten. Sherlock's face turns red and his eyes start to bulge. He coughs and chokes, and Sam watches, his eyes narrowing and turning black and never leaving Sherlock's, and Sherlock's start to close, and he tries to do all these fancy self-defence moves to loosen the hold but he's too weak and Sam is too strong and he watches the life drain out of him, one second at a time –

And then there's a hand on Sam's shoulder, and he's wrenched away from Sherlock, and John punches him in the face. Again.

"What the _fuck_?" Sam yells, hitting John back with a crack when his fist collides, and John manages to stay on his feet, though his nose is visibly broken and blood pours out.

"You alright?" John asks, looking behind Sam at Sherlock. "Fine," comes the hoarse reply. Sam doesn't bother turning around.

"How dare you touch me, you – you _pet,_ " Sam snarls, throwing his hand out, and John flies back against the wall and hangs there, unable to move.

"Sammy, I know you're in there," Dean says slowly, holding his hands up, taking a step forwards. "Just listen to me. Stop this. You're possessed. This isn't you."

"My _god,_ " says Sam, rolling his eyes. "You never stop, do you?"

"Put John down," comes Sherlock's voice from behind him, and the atmosphere calms suddenly, becoming cool and calculating instead of chaotic. "Let Sam go."

Now, Sam's had enough. No one here is appreciating what he's gone through to set this up. Months of planning. He'd had the idea _decades_ ago, and it had been building, fed by rumours and revenge, and then suddenly, here he was, and it was happening, and no one _got_ that, no one _understood,_ not even Sherlock, the one man he thought would have been able to empathise.

Sam drops John, hears the thud. "Okay," he says, one side of his mouth curling upwards. "I'll let Sam go."

He sees Sherlock put the pieces together. "Oh, of course. I'm the only one that hasn't been possessed, aren't I?"

"Saved the best for last."

"I should be flattered, but I'm finding it hard."

"Come on, I did all of this for you."

Sherlock frowns. "I beg your pardon?"

"You haven't worked it out yet?" Sam raises his eyebrows. "I'm disappointed. Well, I'll give you some clues."

* * *

_The lights go off. "Sherlock!" John yells. I change, and stretch out my fingers and arms and legs. I'm gonna be here for a while, I think._

_Somewhere outside this place, the clock strikes six. It's time._


	6. Communication Breakdown

**Notes for the Chapter:**

> Final chapter! There's gonna be an epilogue though, which will answer all the questions (hopefully). Thank you for the comments, you're all awesome. Enjoy the "finale" and tell me what you think! :)

"Fucking hell!" Sherlock shouts, clutching his head. "Stop _fighting!_ "

" _No_ ," says the voice in the back of his head. " _Get out of my head_."

"Why can't you just _work_ with me?" Sherlock yells, bashing the heel of his hand against his forehead. "We can be partners! It'll be magnificent. We can take over the world. You know we could. Your mind, my mind, our power. Just submit to it."

" _I have a partner_."

"I'm not so sure." Sherlock raises his hand and closes his fingers and a chair flies into John's head. He falls to the ground and there's a sickening crack. "Whoops."

" _John_ ," is the voice's only reaction.

The angel walks to John's corpse and presses two fingers to his forehead. "He's dead," he announces.

"Fix him!" Rose says, her eyes wide.

"I can't, my power is being blocked. We need to get John and myself out of this building, or I won't be able to bring him back."

"Well, come on!" Dean says loudly, looking at them all expectantly. "We have to get out anyway, let's friggin' do this."

"How are we gonna get out?" says Sam, whom Dean still hasn't let go of. "It's 6p.m. or whatever, there's obviously something planned."

"That _was_ the thing, Sammy! This is it! John is dead, and we're gonna go the same way if we don't get out of here." Adorable.

"You're no threat to me," Sherlock says casually. "I have no need to kill you."

"Is that what our lives are?" Dean asks, squaring his shoulders. "Pieces in a game?"

"I wouldn't put it that way."

"How would you put it?"

"More eloquently. With better diction."

"You're a dick."

"No, I'm smarter than you. Than all of you." Sherlock smirks. "And now I have the mind of Sherlock Holmes on my side, too. Nothing can stop us."

"He's right," says the Doctor. "Two smartest things in here, combined. We don't stand a chance."

"You got a point?" asks Sam bitterly.

"My point is that we should try doing this." He strides over to the small table and picks it up, leaving the room and heading towards the entrance. There's a crash as he throws the table at the double doors. They remain closed, but the Doctor inspects them closely and says, "The wood's split a little."

"Best plan we have," says Dean, shrugging. He grabs the remainder of the chair that's lying next to John's dead body and joins the Doctor at the doors.

"Stop it," Sherlock says, frowning. "That's not going to work. You're just distracting from my plan."

"Good," says Rose, as her and Sam go to help.

The angel remains crouched by John, both hands on his head. "What are you doing?" Sherlock asks.

"I'm trying," is the angel's curt reply, and he doesn't elaborate.

"This is your fault," Sherlock thinks.

" _It's really not_ ," the voice thinks back, but there's no energy in it.

"John's dead."

" _I can see that_."

"Are you mad at me?"

" _Extremely_."

"What are you gonna do?"

" _I'm not sure yet_."

"Yes you are. I can see it. You're going to kill me."

" _Ah. Yes. We're in the same head. That's going to stunt my planning a little_."

"The angel can't bring him back. I painted sigils that block his power. And they're on the outside, before you get any vandalism ideas."

" _I'll think of something. You know I will_."

"Oh, I'm looking forward to it."

There's a grunt from the entrance. "This isn't _working._ "

"Shut up, Sam."

A piece of wood clatters to the floor. "It's true, Dean, look at it. All we're doing is chipping the paint."

"Well, work harder."

"In this situation, Dean, brute force won't work," Sherlock calls through. "I know this must be hard for you, seeing as it's basically all you know how to do, and how you solve every problem."

Dean strides back in. Of course he does. Always easy to get a rise out of that one. "Listen here, you bastard, I am going to rip you apart as soon as we get out of here, and I mean _soon._ You've been knocking around down there in Hell, ever heard of Alastair?" When Sherlock nods, Dean moves closer, staring into his eyes. "Well, he trained me up real nice. And then I got so good that I tortured the man himself until he _begged_ me to stop. And that's what you've got waiting for you."

Sherlock swallows, and starts to reply, but Dean is pulled away, the Doctor saying, "Don't talk to it, that's what it wants."

"I'm not an _it,_ " Sherlock says, rolling his eyes. "I'm a man. At least, I was."

The Doctor takes Dean's place, looking at Sherlock, his eyes more curious than angry, the fire burning quietly instead of uncontrollably. "Sherlock."

"Nope."

"Sherlock, you have to be in there. Somewhere. Look at John." He points to the body. "Look at him. Sherlock, he's dead. We need to get him outside so that Cas can heal him." He turns to the angel. "Right?"

"Yes, but…" Castiel shakes his head. "It has to be soon. Very soon."

"What? Why?"

"I can bring him back to life, and I can heal any wounds he has, but if we wait too long and his body starts to decompose, well, I can't fix that. If his brain shuts down, then there's nothing I can do."

The Doctor turns back to Sherlock. "See? Sherlock, he'll die. He'll die for good. You need to help us. Tell us how to get out."

"He doesn't know," Sherlock says.

"But you do. And your minds are mixed together. Sherlock, help him."

" _John_ ," comes the voice.

"Shut up," thinks Sherlock hastily.

" _Tell me how to get out of here._ "

"No."

" _Tell me!_ "

"No. I refuse. I want John to die."

There's a pain in his head so intense that he drops to his knees, clutching numbly at his head and grunting. "Stop it!" Sherlock thinks, and it hurts to even do that.

The pain subsides for a moment, and then returns, doubled, and Sherlock screams and then –

"John," says Sherlock, out loud, and his head whips around to where the body lies. "John, oh my god."

"Sherlock?" the Doctor asks.

"Yes, yes, of course. Now, I don't have much time. Do you speak Enochian?" he asks Castiel.

"Yes."

"Good. You have to say something in Enochian in order to escape."

"What is it?"

" _'Sam Winchester wears make up'."_

"Oh, seriously?" Sam moans, throwing his arms up, and Dean holds back his laughter.

"You have to place your hand on the door and say that in Enochian, now hurry up and get out of here," Sherlock says quickly, before his head snaps around and he cries out, dropping to all fours and he can hear Castiel say something he doesn't recognise and the door being opened, and John is carried out, leaking blood from his head and leaving a trail on the floor that Sherlock follows with his eyes, seeing them escape, seeing all of them escape, _no,_ that wasn't the plan, they're not meant to escape. They were meant to be there forever. ?

"You did this," he thinks, anger so intense that he no longer has the control to keep Sherlock in the cage, he can't be dominant when he's this angry, and Sherlock comes bleeding back through the cracks, and he's trying to run out too but the doors have locked and he's trapped and his head is _killing_ him –

* * *

They lay John on the ground ten metres from the double doors while the Doctor and Rose run off to fetch the TARDIS and Sam tries to find somewhere that sells salt. Dean watches as Cas stands up straight, looking at his hands, flexing his fingers. "You good to go?" he asks.

"Almost. My power is returning," Cas replies.

"How long has he got?"

"A few minutes. It'll be alright." He looks at Dean and smiles sadly, and that's confusing, because surely he should be happy that they'll be able to save John's life.

But that's not why Cas is sad, is it? Dean curses himself for being so stupid, so callous and dismissive. Cas is sad because of Dean.

"Listen, Cas, about earlier," he starts, and Cas looks up in surprise, eyes wide and still sad and his mouth open ever so slightly, and Dean remembers how close they'd come to kissing, and how Cas had looked happier then than he'd ever seen him. He wants to say something to make the situation better, he wants to admit his emotions and, like, hug it out or something, but he's never been good at that, not really. He doesn't _know_ how he feels. He can't say anything to help because he doesn't know what he wants to happen.

And Cas sees this. Of course Cas sees this. "It's okay, Dean, you don't need to say anything."

"I wish I could, man. I just need to think some things through, okay?"

"I'm not one for false hope, Dean," Cas says, kneeling next to John and focusing his attention on putting two fingers on his forehead and healing his vast collection of injuries. "I do not wish to be provided with it."

"That's not what I'm trying to do, Cas –"

"Nevertheless, that's what you're doing." His voice is so sad and calm and Dean is so frustrated with himself for not doing anything. "I'd prefer if you didn't try anything at all."

Dean has no response to this, so he closes his mouth and nods and puts his hands in his pockets and tries not to get in the way.

After another thirty seconds, John gasps, coughing and blinking, and Cas helps him sit up slowly.

"What happened?" John asks, looking around.

"The demon was in Sherlock, and it killed you. We're out of the place now, and you're alright," Dean tells him, and puts out a hand, pulling John to his feet.

"Sherlock, where is he?"

"He's still in there."

"What? Are you serious?"

"Yeah. I'm sorry, man."

"No, don't say that, that sounds like you've given up." He runs over to the doors and tries the handle. "It's locked."

Dean shoots Cas a concerned glance and follows John, trying the door himself. It won't budge. "I can't get in."

John turns to him, pale and frowning. "If we can't get in, then Sherlock can't get out. He's trapped."

* * *

_Right. Come on now. Let's talk. Door's locked. You and me._

Is John okay?

_Don't know, don't care._

Why are you doing this? Why me? What's so special about me?

_We'll get to that. Right now, I want you to tell me what you know. What you've worked out about me. I know you have something. I can tell._

I'm new to the whole supernatural world, but I was able to work out a few things, seeing as you used to be human.

_Do tell._

Well, you still have emotions, obviously, seeing as you killed John out of anger and jealousy. From what the Americans said, it doesn't seem like demons and things tend to have emotions, so you're not the regular breed. You're different.

_Are you saying I'm special?_

I don't know enough to make that judgement.

_You are, aren't you?_

No.

_Okay, have you got anything else?_

_Sherlock, you still there?_

_I'll take that as a no._

You haven't given me much to go on. You're very good at clearing away the evidence. I'd clap sarcastically if I currently had use of my hands.

_Thank you._

I didn't mean that as a compliment.

_I'm taking it as one and you can't stop me. Now, would you like me to tell you what I am?_

I'm not sure.

_There's no way you could work it out. Not even the Americans could figure it out, and they've been doing this for years._

I'm sure if I had their experience I'd be able to handle the task, but as it is, I've known of your kind's existence for nine hours. Go on then, tell me.

_Well, it's a long story. Are you sitting comfortably?_

No. I can't sit and there's a demon in half of my head.

_Good, then I'll begin. My name is Moriarty. I lived twenty years ago in Ireland._

So that's why your accent sounds so warped. You're not even English.

_Shh, I'm telling a story. Now, all my life I'd been smarter than the other kids, and I'd known it. I was a bit of a psychopath, but of course, I kept it hidden, because it was easy. Because I could manipulate people easy as pouring a bowl of cereal. It was rather fun as a child, because I could get things, like other people's toys and money and lunch, but when I reached double figures it started to burn. I was trapped inside my own head. Nothing on earth was entertaining enough for me. Staying alive, it started to bore me. I wanted something else._

_So I got into the supernatural. I studied for years, ran away when I was thirteen and travelled around the world, collected books and met people and eventually I happened upon something called a crossroads demon. And by then, I knew what I wanted to ask for. I wanted to be a demon._

Why the hell would you want that?

_Look at me, Sherlock. Look at the power I have. Look at what I can do. Because I asked for it, they could mould me into a demon unlike anyone had ever seen before. It's not staying alive anymore, oh no. It's so much more than that. I've been to Hell. And it's more vivid than anything I could ever have hoped for._

You still haven't told me why you're doing all this, and what my involvement is in it.

 _Well, you see, it still wasn't enough. I was still bored. I was torturing the wicked and taking baths in virgin blood and stuff like that and I looked at my life and I went, this isn't enough. So I went back up to earth and I listened for a while. And you're so_ loud _, Sherlock! You try and keep quiet, but even without your media fame, you're still so loud. So cocky, so magnificent. I was drawn to you._

Oh, great.

_And I started to form an idea, because there's nothing better for people like us than the game. I've enjoyed this immensely, moving you all like pieces on a chess board. And you, Sherlock, you're the king. And this is checkmate._

Actually, it's check, because you haven't actually won yet.

_Haven't I?_

No, because I'm still alive, and while I'm alive, I'm going to try and beat you. And what do you mean, people like us?

 _You have the same problem, surely. The need for something more. The_ constant _need, the itching in your mind, the need to grab something with your bare hands._

Of course. But I don't kill people. I help them.

_There's not that much of a difference._

Don't get deep with me, there's a big difference. I'm not going to empathise with you just because we both get bored. You killed John. I don't care if they brought him back to life, you still killed him, and for that, I'm going to kill you.

_And how exactly do you plan on doing that, my dear?_

I don't know. I'm working on it.

* * *

"Dean!" he hears, and turns around to find Sam running towards them, shopping bags in both his hands. "Supermarket was open. I got some paint and salt and bottles of water."

"Awesome, nice job. You got a rosary?"

"Yeah, I went into a church and stole one off the side." He smirks, embarrassed. "I thought, y'know, priorities."

"I don't think God will be angry with you," says Cas, taking one of the bags while Dean takes the other. Dean opens it and takes out the paint can and brush, making a B-line for the sides of the building where the angel-blocking sigils are painted. He crosses them through before painting a demon trap just outside the entrance.

"We have to go in there," says John quietly, cornering Dean while he works.

"We can't. It's suicide. Best thing to do is wait until they come out."

"They _won't_ come out. It could kill Sherlock."

"It won't kill Sherlock."

"It killed _me_!"

"Oh yeah. Good point." He finishes the trap and sighs, putting the tin down. "John, I get that he's your partner and everything, but, look, wouldn't he want you to be logical? That's his thing, right?"

"If this were Sam in there, or Cas, what would you do?" He looks at Dean expectantly, and there's a little bit of smugness in there, because he knows he's right, and he knows Dean knows, too.

"Fuck, John, you just came back from the dead! You're not strong enough!"

"I've never been strong enough to deal with Sherlock, but I do it anyway." He walks off towards the sound of the TARDIS that has started quietly a few metres away, and soon Dean is watching a blue box appear from thin air and questioning why the hell he's not drinking beer and watching _Dr. Sexy MD_ right now.

When the door opens and it's bigger on the inside, Dean says, "Fuck it, I'm in," and starts blessing water and teaching John about how to use salt against the demon because it seems like the word "impossible" doesn't really hold much weight around here anymore.

* * *

_So, tell me something. Why John?_

He's a conductor of light.

_You keep him around because you don't know how to change the light bulbs?_

No, I mean –

_I know what you meant, I just wanted to say that. But I assume that he actually does change the light bulbs._

Yes. But I do know how. Also he gets the milk.

_That all?_

He provides companionship. He's my friend.

_I could be your friend._

About that. Do you plan on possessing me forever? Because with both of us in here we've been standing rigid for about four minutes.

_Oh, didn't I tell you? I'm integrating our minds as we speak. I'm downloading myself into your system, if you will._

What?

_It's almost done, too. About eighty percent. Soon you won't be able to get me out. Ever._

You can do that?

_Yes. Only me._

I don't want that.

_Stop me, then._

I… I don't have a plan.

_No, you don't._

Oh, god. I can't stop you.

_No, you can't._

I'm going to kill you.

_No, you're not._

* * *

"We're going to kill the demon," John says to the Doctor and Rose as they emerge. To his surprise, they don't look particularly scared or worried. All that happens is Rose says, "Do we have to kill him? Isn't there a chance that he's nice?"

"We're killing it," Dean says firmly. "It's the only way to make sure we never end up in _Hotel California_ over there again." He waves a hand towards the building.

"Okay then. Killing. I can do that. God knows I've done it before," says the Doctor, and Rose looks up at him but he doesn't look back. "What can we do to help?"

"Just stay out of the way," John says.

The Doctor pouts. "That's not very like me. Oh, hang on." He pops back to the blue box and John frowns in confusion. He looks to Rose for an answer but she's frowning, too. The Doctor runs back out after thirty seconds or so, brandishing three keys and a smile.

John looks at him blankly. "What are those?"

"Keys!"

"Yes, I can see that."

"See, they're _TARDIS_ keys, meaning they have a perception filter around them. Bit of fiddling, you wear this around your neck, he won't see you coming."

"Awesome," Sam says, and grins. Dean smiles a little. John feels like he could kiss the strange man with the strange hair.

"Okay. Do we have a plan?" John asks, not too optimistic about the answer. Sam gives him a look that proves his suspicions right. "Okay, no plan. Except to kill the damn thing. Can we do that without harming Sherlock?"

"Depends whether we want to kill the thing or send it back to Hell," Dean answers, stripping off the plastic from the salt bottles. "If we want to kill it, we need the knife, which we had before we went in, so it's gotta be around here somewhere. We stab Sherlock, and he might survive that, but the demon won't."

"Alternative?" John asks through gritted teeth.

"We douse it in salt, get it in a demon trap and exorcise it."

"But that won't kill it?"

"No."

"It could come back?"

"Yeah. Look, man, our friend Bobby got stabbed when there was a demon in him and he's fine now."

"He lost the use of his legs," Cas says, and Dean glares. "Oh, uh, but he's fine now, yeah."

Everyone is looking at John; they seem to have reached a mutual agreement that this is John's decision. He takes a deep breath and tries to think logically. He wants the thing dead. So does everyone around him. Most likely, Sherlock does too. He's a doctor, he knows the chances of surviving a stab wound are pretty good, especially with a spaceship that can apparently travel anywhere instantaneously. The angel guy, Cas, he can heal Sherlock as soon as the thing is gone, right? If not, they can still get Sherlock to a hospital in about a minute. It's obvious what the right thing to do is. But it scares him. God, he's so fed up of being scared.

But that's the point of this. To kill the bloody thing once and for all.

"Let's kill it," he says, and there's a collective sigh of relief. "Cas, you can fix him, right? You can heal him."

"Yes, as long as my power is functioning properly, which it should be seeing as Dean painted over the sigils."

"Right. Right, good. Okay."

They stand there in a circle and there's the overhanging need for a pep talk, but John has no idea how to give one.

"Well," says the Doctor suddenly, clapping his hands together. "Right. No plan, no knowledge of what this thing is that means it's so powerful, no plan, no demon-killing knife, and no plan. But you know what we do have?"

"A can-do attitude?" Dean asks sarcastically.

"Exactly!" The Doctor grins. "And teamwork! And intelligence, and free will, and morality."

"And love," Rose cuts in, and the Doctor nods.

"Yep, love. Emotion. All good things."

"And he can't take that away from us!"

"Never!"

John sighs. "Oh, god, we're all going to die."

"Where do you think our weapons will be?" Cas asks.

"Probably somewhere inside," Sam answers. "They were taken as soon as we went through the door, and one of these sigils is probably responsible for that. Dean, are you sure you got them all?"

"On this side, yeah." Dean frowns. "There might be a back way."

"Alright, let's check that out." He walks off towards the other side of the building and Dean follows.

"Anything we can do?" John asks Cas.

"No," Cas replies.

"Oh. Good."

They stand in patient silence.

* * *

Dean and Sam walk along the wall, looking closely for any sigils. Sam breaths in heavily as he goes. It's good to be outside again. He opens his shirt a little to let the cool air soothe the burn where his anti-possession tattoo used to be. He'll get Cas to fix that up soon enough. For now, they have other priorities.

"Doesn't seem to be anything on here," Dean says. He's right; the wall appears to be blank.

"Check under those trash bags," Sam says, pointing to the bags stacked up against the wall. Together they pull them away from the wall, and Sam grins as they reveal a sigil painted low, by the floor. "I'm a genius."

"You're an asshole."

They pull out the paint and start crossing it through. "This seems like a one person job," Dean comments after a few seconds. "Wanna go back to the others? I got this covered."

Sam puts down his paint but stays crouched next to Dean.

"What, Sam?"

"You know what. We shouldn't be doing this. It's not a good plan."

"We don't even _have_ a plan, how can it be bad?" Dean jokes.

"That's _why_ it's bad, Dean. This thing is more powerful than any demon we've ever come across. Hell, it's not natural, in more than one sense. We might not even find the knife. If we don't, we're dead."

"We'll find the knife," Dean says firmly. "Don't worry."

"I'm just saying, it's smarter to just lock it in there until we can get help. Put salt at every door, paint more demon traps. That kind of thing."

Dean sighs and puts his paint can down heavily. "Sam, Sherlock's in there. We can't just leave him."

"That's not Sherlock anymore, Dean. I know what it's like to be possessed by that thing, and you do too. You have no control."

"And that's exactly why we have to help him. Besides, that thing has a weird interest in Sherlock that I don't like the sound of. Better to get him out of there before he gets hurt."

"Why are you so attached to this guy all of a sudden? You think he's a douchebag."

"Yeah, but..." Dean rolls his eyes at himself. "John seems like a nice guy, and Sherlock means a lot to him. I just want to do the right thing here."

Sam looks at him steadily for a few seconds. "I'm just trying to protect you."

"Yeah, well, don't, okay? We're not gonna die. We're gonna find the knife and kill the thing and Cas is gonna heal Sherlock and we're all gonna go our separate ways and walk into the sunset holding hands."

He gets up and walks back to the others. Sam puts his face in his hands, because seriously, that's the entire plan they have right there.

* * *

"I'll go first," says John, and Dean laughs and replies, "Not a chance. I'll take point, Sam you come right behind me. We'll go looking for the weapons. Rest of you throw salt at it, keep it busy until we find the knife. Cas, you keep a look out, protect them, heal if necessary." Cas nods.

"Everyone ready?" Dean says, looking around the group, face grim. Sam nods, and John wraps his hand firmly around the bottle of salt he's holding. The Doctor and Rose exchange comforting glances and Cas looks at Dean. "Okay. Doctor, open the door."

The Doctor raises his arm and the sonic screwdriver emits a blue light and a high-pitched noise and there's a clicking as the door opens.

Dean shoulders it open and looks around before whispering, "Clear." They line in after him, moving as quietly as possible. Sam and Dean split off to go and look for their weapons, and Cas moves to the front, glancing round the door into the room they last saw Sherlock in.

"You're not going to be able to sneak up on me. Don't even try."

Cas pushes the door all the way open to reveal Sherlock standing there, perfectly, unnaturally still, and he's smiling. The room seems colder. Rose knows better than to disregard this fact. Something's changed. Sherlock's possession is different. Why isn't his body moving?

"Just over a minute left," Sherlock says, seeing the suspicious look on her face. "I'm taking this body for good, one limb at a time. Right now I can only get the face and the voice to work, but we're getting there."

"What are you talking about?" John asks, coming to stand by Cas's side in front of Rose. Cas holds out an arm, trying to keep him back, but John brushes it away, moves closer. "You can do that?"

"Yes."

"That's not right," Cas says. "You're not normal."

Sherlock pouts. "That's not a very nice thing to say."

"Get out of him," John says, voice low and threatening.

"Well, no."

"I swear to god."

"What? What can you do?"

"This." He pulls the salt out from behind his back and throws it at Sherlock's face. Sherlock howls and steam rises from his skin and he claws at his face, and Rose looks at John and sees this his jaw is set tightly and he's looking away.

"That," says Sherlock, straightening up and brushing down his suit, "stings. At least I can use the arms now."

"Is Sherlock still in there?" the Doctor asks, his voice coming from beside Rose.

"Yes, of course. I don't just want his body, I'm not that shallow. I want his mind, too."

John walks around Sherlock, looking him up and down. Sherlock turns with him, amused. "You're not going to hurt him?" John asks warily.

"No, I'm not," Sherlock says when he's facing John, back to the rest of them, assuming he's safe seeing as his power is so immense.

"Well, that's a shame," Dean says from behind him. "Because I am."

Sherlock frowns, and flicks a finger without bothering to raise his arm. Dean and Sam go flying backwards from their position near the doorway into the wall opposite. "Fuck!" Dean shouts, while Sam screws up his face in obvious pain. The demon knife lies on the other side of the room.

Sherlock just shakes his head sadly. "I really wish you'd cooperate. It's so much more fun if you play along."

Rose looks down at the knife at her feet.

"'Cos then I don't have to watch you try and be clever!" Sherlock says, still shaking his head and approaching Sam and Dean, who maintain eye contact.

Rose looks at Sherlock's back.

"It's sad, really, I get no enjoyment from it." He pauses. "Well, that's a lie. But I prefer to join in than just watch."

Rose picks up the knife and the Doctor moves beside her, but she ignores him, doesn't look at him, just focuses on the target in front of her. Four steps forwards, she thinks. Move your right arm. Do it. Do it now. _Do_ it.

"Anyway, legs are working, look at that. Almost done, just the admin stuff now, like the calibration of the –"

His speech is interrupted by sudden knife in his back. His mouth opens as the orange light flashes from the wound, and he only has time to say, "Oh," before falling forwards onto the ground.

"Heal him," John says to Cas immediately, not even pausing for breath. "Now."

Cas approaches Sherlock, places his hand on the stab wound, and shunts a portion of his grace out into his fingertips, letting the healing power seep through his skin, and feels the wound close and Sherlock's vital signs return to normal. He rolls him over onto his back.

"Can you wake him up?" John asks.

"No, we have to wait. The damage in his head is repairing itself. If I wake him up it could prevent the healing. We shouldn't move him, either."

John looks at Cas wearily, and it's clear that he just wants to go home and have some tea. "Okay, well, you can all go, I'll wait here until he wakes up."

"Nuh-uh, no way," Rose says, shaking her head. "We're waiting with you. All of us."

"You really don't have to."

"We insist," says the Doctor, shooting a _be nice_ look to Dean and Sam.

"Alright, we can hang around for a couple hours to see if he's okay," Dean says, nodding. "Cas, can I talk to you for a sec?"

Cas nods and follows Dean out of the room and through the corridors to the store room. It almost makes Cas laugh; this is how much he doesn't want Sam to hear, he's taking them to the other side of the building. Dean closes the door once they're inside and it strikes Cas that this is exactly where they stood when they'd been about to kiss. This obviously wasn't on purpose, maybe a sub-conscious association, and probably not one Dean has noticed.

"Sorry to bring you all the way over here," Dean says, and his face is already going red. He shoves his hands into his pockets and takes a few slow breaths before looking into Cas's eyes. "So I've been thinking."

"Dean -"

"Let me talk. So I've been thinking, and that's not something I've done about this subject before. I never thought about the possibility of me and you before. That's why I was so shitty about the whole thing. Because I literally didn't know what to friggin' _do._ "

Cas nods. This is an acceptable answer. It doesn't hurt his feelings. It just makes him a little sad. "So now you've been thinking?"

"Yeah, I was getting to that." He looks so uncomfortable, Cas wants to tell him to stop, but he knows that he shouldn't. "I was thinking and, well, I suppose I wouldn't be completely opposed to trying it out. I mean, I'm an open minded guy. And... yeah."

Cas looks at him and tries to keep his face calm when he's silently cursing his newfound emotions because of how much they hurt. "Right. Thank you for your generous offer, but no thank you."

Dean shakes his head and says, "Fuck, wait, shit, that's not what I wanted to say. Can I start again? I'm gonna start again. Okay. I was thinking, and seeing as I'm emotionally idiotic, I'm not very good at, uh, _voicing_ things. So uh, basically, um." He scratches the back of his neck. "I like you."

Cas stares at him and Dean laughs at himself, saying, "I'm like a fucking middle-schooler, I'm sorry."

"Does this mean that you have romantic feelings towards me?" Cas asks, confused. He knows that Dean likes him, they're friends.

"Uh. Yeah. Yes." His face is beet red.

Cas smiles. "I like you too."

"Good. Great. Okay."

"Well done. That looked... hard."

"You should be honoured."

"I am. Are you sweating?"

"A little."

Cas laughs. He doesn't have a response, and Dean doesn't say anything either, so they're left to just listen to the air between them, and there's so much in it, but surprisingly little space between them, and it was right here that Dean had put his hands on Cas's hips and almost, almost kissed him, and this time it was the real Dean and if he leaned in just a little, if he stepped forwards, he could kiss him, and Dean wouldn't stop him.

Dean has that look in his eye that the demon had had, but this time, Cas looks at him, and he can tell that it's Dean, that he's genuine. He does it, he steps forwards hesitantly and places his hands on Dean's waist and Dean looks at him, filled with surprise and wonder and excited nerves, and when Cas kisses him, Dean smiles.

* * *

"Are you alright?" the Doctor murmurs to Rose. They sit on the floor, leaning against the wall, far enough away from other people that they can talk privately.

"Yeah," she says, then takes a deep breath. "Yeah, I think I am. As long as Sherlock's alright, I'll be okay."

"That was an amazing thing you did."

Rose looks at him steadily for a moment, and then a grin slides onto her face. "I know."

"You saved us all."

"I _know_!"

"I'm just saying," he says defensively, holding up his hands, but he's grinning too, now, and they smile at each other for a while before she pulls him into a hug.

"We're safe now?" she says into his shoulder.

"Promise," he replies. "I'll always protect you."

She smiles, even though he can't see. "I know."

* * *

"John," is the first thing Sherlock says when he stirs, and Sam rolls his eyes.

John helps him sit up and fusses profusely, handing him a glass of water and asking him to count how many fingers he's holding up and "follow my finger with your eyes" and in the end Sherlock just says, "Please stop," so John does, and sits down beside him, looking concerned.

"How do you feel?" Cas asks.

"Fine."

"Regarding your mental state?"

"Fine."

"What happened in there?" John asks.

Sherlock frowns. "I don't remember."

"You should," Cas says, brow furrowing.

"Well, I don't. I think I'd know if I did, my brain is very good."

"Good to know his personality's the same," John mutters.

"So we'll never know why it was so powerful," says Sam, sounding disappointed. "What was different about it."

"Wasn't that different," says Dean. "Still killed it with the knife."

"So it's definitely dead?" asks Rose.

"Yep."

"It can't come back?"

"Nope."

Rose nods. "Good."

John helps Sherlock to his feet and supports him as they walk out of the place, with Sherlock complaining the whole way about how unnecessary it is and John telling him to shut up. Sam, Dean and Cas walk out after them, and Rose and the Doctor follow, the Doctor grabbing Rose's hand as they go.

"Well, I suppose this is it," says John, and puts out his hand to each of them in turn. "It's been an experience."

"Keep him safe," the Doctor says, smiling. "Don't get in too much trouble."

Sherlock scoffs, but John says, "I'll try," before he can say anything. He nods, before leading Sherlock off towards a main road to hail a cab.

"Right, Cas, can you get us back to Bobby's?" Dean asks, and Cas nods in response. "Okay, well. See you around." Dean waves vaguely, obviously eager to get out of there.

"Thanks for everything," Rose says, smiling broadly, and Dean smiles back and says, "Thank _you_ for saving our asses."

"You gonna be alright?" Sam asks. "You know, with the fact that all this supernatural stuff exists?"

"Ah, we're fine," the Doctor says, grinning. "Problem is, are you gonna be alright with the aliens?"

"Let's not think about that," Sam says, and laughs. "Bye, guys."

Sam and Dean put their hands on Cas's shoulders and Cas smiles and nods before they all disappear in a gush of wind and a flutter of wings.

And then it's just them. The Doctor and Rose. Standing alone on a road like nothing's happened.

Rose turns to him and says, "Are we, though?"

"Are we what?"

"Gonna be alright with the supernatural? I mean, what can we do?"

The Doctor steps back, tugging her by the hand, and they start walking back towards the TARDIS. Before he opens the door, he turns around, pulling her into a tight hug. She laughs a little in surprise, but then wraps her arms around his back and breathes in the smell of his old coat. When he lets go, he looks at her for a few seconds and says, "We keep our eyes open." They step inside the TARDIS, and a few moments later, the street is empty.


End file.
